diff --git a/libraries/wutdevoptab/devoptab_fs_chdir.c b/libraries/wutdevoptab/devoptab_fs_chdir.c
index 7458909..1fa8e42 100644
--- a/libraries/wutdevoptab/devoptab_fs_chdir.c
+++ b/libraries/wutdevoptab/devoptab_fs_chdir.c
@@ -2,32 +2,28 @@
 
 int
 __wut_fs_chdir(struct _reent *r,
-               const char *name)
+               const char *path)
 {
-   FSStatus rc;
-
-   if (name == NULL) {
-         return -1;
-   }
-
-   char *path = __wut_fs_fixpath(r, name);
+   FSStatus status;
+   FSCmdBlock cmd;
 
    if (!path) {
-      r->_errno = ENOMEM;
+      r->_errno = EINVAL;
       return -1;
    }
 
-   // Set up command block
-   FSCmdBlock fsCmd;
-   FSInitCmdBlock(&fsCmd);
-
-   rc = FSChangeDir(__wut_devoptab_fs_client, &fsCmd, path, -1);
-   free(path);
-
-   if (rc >= 0) {
-      return 0;
+   char *fixedPath = __wut_fs_fixpath(r, path);
+   if (!fixedPath) {
+      return -1;
    }
 
-   r->_errno = __wut_fs_translate_error(rc);
-   return -1;
+   FSInitCmdBlock(&cmd);
+   status = FSChangeDir(__wut_devoptab_fs_client, &cmd, fixedPath, -1);
+   free(fixedPath);
+   if (status < 0) {
+      r->_errno = __wut_fs_translate_error(status);
+      return -1;
+   }
+
+   return 0;
 }
diff --git a/libraries/wutdevoptab/devoptab_fs_chmod.c b/libraries/wutdevoptab/devoptab_fs_chmod.c
index 4b891f7..15cb29f 100644
--- a/libraries/wutdevoptab/devoptab_fs_chmod.c
+++ b/libraries/wutdevoptab/devoptab_fs_chmod.c
@@ -5,25 +5,27 @@ __wut_fs_chmod(struct _reent *r,
                const char *path,
                mode_t mode)
 {
-   FSStatus rc;
-   char *path_fix = __wut_fs_fixpath(r, path);
+   FSStatus status;
+   FSCmdBlock cmd;
 
-   if (!path_fix) {
-      r->_errno = ENOMEM;
+   if (!path) {
+      r->_errno = EINVAL;
       return -1;
    }
 
-   // Set up command block
-   FSCmdBlock fsCmd;
-   FSInitCmdBlock(&fsCmd);
-
-   rc = FSChangeMode(__wut_devoptab_fs_client, &fsCmd, path_fix, (FSMode)mode, -1);
-   free(path_fix);
-
-   if (rc >= 0) {
-      return 0;
+   char *fixedPath = __wut_fs_fixpath(r, path);
+   if (!fixedPath) {
+      return -1;
    }
 
-   r->_errno = __wut_fs_translate_error(rc);
-   return -1;
+   FSInitCmdBlock(&cmd);
+   status = FSChangeMode(__wut_devoptab_fs_client, &cmd, fixedPath,
+                         (FSMode)mode, -1);
+   free(fixedPath);
+   if (status < 0) {
+      r->_errno = __wut_fs_translate_error(status);
+      return -1;
+   }
+
+   return 0;
 }
diff --git a/libraries/wutdevoptab/devoptab_fs_close.c b/libraries/wutdevoptab/devoptab_fs_close.c
index 8ad28fa..8678f48 100644
--- a/libraries/wutdevoptab/devoptab_fs_close.c
+++ b/libraries/wutdevoptab/devoptab_fs_close.c
@@ -4,19 +4,22 @@ int
 __wut_fs_close(struct _reent *r,
                void *fd)
 {
-   FSStatus rc;
-   __wut_fs_file_t *file = (__wut_fs_file_t *)fd;
+   FSStatus status;
+   FSCmdBlock cmd;
+   __wut_fs_file_t *file;
 
-   // Set up command block
-   FSCmdBlock fsCmd;
-   FSInitCmdBlock(&fsCmd);
-
-   rc = FSCloseFile(__wut_devoptab_fs_client, &fsCmd, file->fd, -1);
-
-   if (rc >= 0) {
-      return 0;
+   if (!fd) {
+      r->_errno = EINVAL;
+      return -1;
    }
 
-   r->_errno = __wut_fs_translate_error(rc);
-   return -1;
+   FSInitCmdBlock(&cmd);
+   file = (__wut_fs_file_t *)fd;
+   status = FSCloseFile(__wut_devoptab_fs_client, &cmd, file->fd, -1);
+   if (status < 0) {
+      r->_errno = __wut_fs_translate_error(status);
+      return -1;
+   }
+
+   return 0;
 }
diff --git a/libraries/wutdevoptab/devoptab_fs_dirclose.c b/libraries/wutdevoptab/devoptab_fs_dirclose.c
index adde150..73aa96a 100644
--- a/libraries/wutdevoptab/devoptab_fs_dirclose.c
+++ b/libraries/wutdevoptab/devoptab_fs_dirclose.c
@@ -4,19 +4,22 @@ int
 __wut_fs_dirclose(struct _reent *r,
                   DIR_ITER *dirState)
 {
-   FSStatus rc;
+   FSStatus status;
+   FSCmdBlock cmd;
+   __wut_fs_dir_t *dir;
 
-   // Set up command block
-   FSCmdBlock fsCmd;
-   FSInitCmdBlock(&fsCmd);
-
-   __wut_fs_dir_t *dir = (__wut_fs_dir_t *)(dirState->dirStruct);
-   rc = FSCloseDir(__wut_devoptab_fs_client, &fsCmd, dir->fd, -1);
-
-   if (rc >= 0) {
-      return 0;
+   if (!dirState) {
+      r->_errno = EINVAL;
+      return -1;
    }
 
-   r->_errno = __wut_fs_translate_error(rc);
-   return -1;
+   FSInitCmdBlock(&cmd);
+   dir = (__wut_fs_dir_t *)(dirState->dirStruct);
+   status = FSCloseDir(__wut_devoptab_fs_client, &cmd, dir->fd, -1);
+   if (status < 0) {
+      r->_errno = __wut_fs_translate_error(status);
+      return -1;
+   }
+
+   return 0;
 }
diff --git a/libraries/wutdevoptab/devoptab_fs_dirnext.c b/libraries/wutdevoptab/devoptab_fs_dirnext.c
index 1b01306..8c2ec21 100644
--- a/libraries/wutdevoptab/devoptab_fs_dirnext.c
+++ b/libraries/wutdevoptab/devoptab_fs_dirnext.c
@@ -6,44 +6,40 @@ __wut_fs_dirnext(struct _reent *r,
                  char *filename,
                  struct stat *filestat)
 {
-   FSStatus rc;
-   __wut_fs_dir_t *dir = (__wut_fs_dir_t *)(dirState->dirStruct);
+   FSStatus status;
+   FSCmdBlock cmd;
+   __wut_fs_dir_t *dir;
 
-   // Set up command block
-   FSCmdBlock fsCmd;
-   FSInitCmdBlock(&fsCmd);
-
-   // Fetch the next dir
-   memset(&dir->entry_data, 0, sizeof(dir->entry_data));
-   rc = FSReadDir(__wut_devoptab_fs_client, &fsCmd, dir->fd, &dir->entry_data, -1);
-
-   if (rc < 0) {
-      // There are no more entries; ENOENT signals end-of-directory
-      r->_errno = ENOENT;
+   if (!dirState || !filename || !filestat) {
+      r->_errno = EINVAL;
       return -1;
    }
 
-   if (rc >= 0) {
-      memset(filestat, 0, sizeof(struct stat));
-
-      // Fill in the stat info
-      filestat->st_ino = 0;
-
-      if (dir->entry_data.info.flags & FS_STAT_DIRECTORY) {
-         filestat->st_mode = S_IFDIR;
-      } else {
-         filestat->st_mode = S_IFREG;
-      }
-
-      filestat->st_uid = dir->entry_data.info.owner;
-      filestat->st_gid = dir->entry_data.info.group;
-      filestat->st_size = dir->entry_data.info.size;
-
-      memset(filename, 0, NAME_MAX);
-      strcpy(filename, dir->entry_data.name);
-      return 0;
+   FSInitCmdBlock(&cmd);
+   dir = (__wut_fs_dir_t *)(dirState->dirStruct);
+   memset(&dir->entry_data, 0, sizeof(dir->entry_data));
+   status = FSReadDir(__wut_devoptab_fs_client, &cmd, dir->fd, &dir->entry_data,
+                      -1);
+   if (status < 0) {
+      r->_errno = __wut_fs_translate_error(status);
+      return -1;
    }
 
-   r->_errno = __wut_fs_translate_error(rc);
-   return -1;
+   // Fill in the stat info
+   memset(filestat, 0, sizeof(struct stat));
+   filestat->st_ino = 0;
+
+   if (dir->entry_data.info.flags & FS_STAT_DIRECTORY) {
+      filestat->st_mode = S_IFDIR;
+   } else {
+      filestat->st_mode = S_IFREG;
+   }
+
+   filestat->st_uid = dir->entry_data.info.owner;
+   filestat->st_gid = dir->entry_data.info.group;
+   filestat->st_size = dir->entry_data.info.size;
+
+   memset(filename, 0, NAME_MAX);
+   strcpy(filename, dir->entry_data.name);
+   return 0;
 }
diff --git a/libraries/wutdevoptab/devoptab_fs_diropen.c b/libraries/wutdevoptab/devoptab_fs_diropen.c
index 2af0ea3..6156891 100644
--- a/libraries/wutdevoptab/devoptab_fs_diropen.c
+++ b/libraries/wutdevoptab/devoptab_fs_diropen.c
@@ -6,35 +6,31 @@ __wut_fs_diropen(struct _reent *r,
                  const char *path)
 {
    FSDirectoryHandle fd;
-   FSStatus rc;
+   FSStatus status;
+   FSCmdBlock cmd;
+   __wut_fs_dir_t *dir;
 
-   if (path == NULL) {
+   if (!dirState || !path) {
+      r->_errno = EINVAL;
       return NULL;
    }
 
-   char *path_fixed = __wut_fs_fixpath(r,path);
-
-   if (!path_fixed) {
-      r->_errno = ENOMEM;
+   char *fixedPath = __wut_fs_fixpath(r, path);
+   if (!fixedPath) {
       return NULL;
    }
 
-   // Set up command block
-   FSCmdBlock fsCmd;
-   FSInitCmdBlock(&fsCmd);
-
-   __wut_fs_dir_t *dir = (__wut_fs_dir_t *)(dirState->dirStruct);
-   rc = FSOpenDir(__wut_devoptab_fs_client, &fsCmd, path_fixed, &fd, -1);
-
-   if (rc >= 0) {
-      dir->magic = FS_DIRITER_MAGIC;
-      dir->fd    = fd;
-      memset(&dir->entry_data, 0, sizeof(dir->entry_data));
-      free(path_fixed);
-      return dirState;
+   FSInitCmdBlock(&cmd);
+   dir = (__wut_fs_dir_t *)(dirState->dirStruct);
+   status = FSOpenDir(__wut_devoptab_fs_client, &cmd, fixedPath, &fd, -1);
+   free(fixedPath);
+   if (status < 0) {
+      r->_errno = __wut_fs_translate_error(status);
+      return NULL;
    }
 
-   free(path_fixed);
-   r->_errno = __wut_fs_translate_error(rc);
-   return NULL;
+   dir->magic = FS_DIRITER_MAGIC;
+   dir->fd    = fd;
+   memset(&dir->entry_data, 0, sizeof(dir->entry_data));
+   return dirState;
 }
diff --git a/libraries/wutdevoptab/devoptab_fs_dirreset.c b/libraries/wutdevoptab/devoptab_fs_dirreset.c
index 36d3384..4cf6610 100644
--- a/libraries/wutdevoptab/devoptab_fs_dirreset.c
+++ b/libraries/wutdevoptab/devoptab_fs_dirreset.c
@@ -4,20 +4,22 @@ int
 __wut_fs_dirreset(struct _reent *r,
                   DIR_ITER *dirState)
 {
-   FSStatus rc;
+   FSStatus status;
+   FSCmdBlock cmd;
+   __wut_fs_dir_t *dir;
 
-   // Set up command block
-   FSCmdBlock fsCmd;
-   FSInitCmdBlock(&fsCmd);
-
-   __wut_fs_dir_t *dir = (__wut_fs_dir_t *)(dirState->dirStruct);
-   rc = FSRewindDir(__wut_devoptab_fs_client, &fsCmd, dir->fd, -1);
-
-   if (rc >= 0) {
-      return 0;
+   if (!dirState) {
+      r->_errno = EINVAL;
+      return -1;
    }
 
-   r->_errno = __wut_fs_translate_error(rc);
-   return -1;
-}
+   FSInitCmdBlock(&cmd);
+   dir = (__wut_fs_dir_t *)(dirState->dirStruct);
+   status = FSRewindDir(__wut_devoptab_fs_client, &cmd, dir->fd, -1);
+   if (status < 0) {
+      r->_errno = __wut_fs_translate_error(status);
+      return -1;
+   }
 
+   return 0;
+}
diff --git a/libraries/wutdevoptab/devoptab_fs_fchmod.c b/libraries/wutdevoptab/devoptab_fs_fchmod.c
index ecab35a..a15ffeb 100644
--- a/libraries/wutdevoptab/devoptab_fs_fchmod.c
+++ b/libraries/wutdevoptab/devoptab_fs_fchmod.c
@@ -5,7 +5,7 @@ __wut_fs_fchmod(struct _reent *r,
                 void *fd,
                 mode_t mode)
 {
-   //TODO: FSChangeMode and FSStatFile?
+   // TODO: FSChangeMode and FSStatFile?
    r->_errno = ENOSYS;
    return -1;
 }
diff --git a/libraries/wutdevoptab/devoptab_fs_fstat.c b/libraries/wutdevoptab/devoptab_fs_fstat.c
index 4da5021..01d346f 100644
--- a/libraries/wutdevoptab/devoptab_fs_fstat.c
+++ b/libraries/wutdevoptab/devoptab_fs_fstat.c
@@ -5,26 +5,30 @@ __wut_fs_fstat(struct _reent *r,
                void *fd,
                struct stat *st)
 {
-   FSStatus rc;
-   FSStat fsstat;
-   __wut_fs_file_t *file = (__wut_fs_file_t *)fd;
+   FSStatus status;
+   FSStat fsStat;
+   FSCmdBlock cmd;
+   __wut_fs_file_t *file;
 
-   // Set up command block
-   FSCmdBlock fsCmd;
-   FSInitCmdBlock(&fsCmd);
-
-   rc = FSGetStatFile(__wut_devoptab_fs_client, &fsCmd, file->fd, &fsstat, -1);
-
-   if (rc >= 0) {
-      memset(st, 0, sizeof(struct stat));
-      st->st_size = fsstat.size;
-      st->st_uid = fsstat.owner;
-      st->st_gid = fsstat.group;
-      st->st_nlink = 1;
-      st->st_mode = fsstat.mode;
-      return 0;
+   if (!fd || !st) {
+      r->_errno = EINVAL;
+      return -1;
    }
 
-   r->_errno = __wut_fs_translate_error(rc);
-   return -1;
+   FSInitCmdBlock(&cmd);
+   file = (__wut_fs_file_t *)fd;
+   status = FSGetStatFile(__wut_devoptab_fs_client, &cmd, file->fd, &fsStat,
+                          -1);
+   if (status < 0) {
+      r->_errno = __wut_fs_translate_error(status);
+      return -1;
+   }
+
+   memset(st, 0, sizeof(struct stat));
+   st->st_size = fsStat.size;
+   st->st_uid = fsStat.owner;
+   st->st_gid = fsStat.group;
+   st->st_nlink = 1;
+   st->st_mode = fsStat.mode;
+   return 0;
 }
diff --git a/libraries/wutdevoptab/devoptab_fs_fsync.c b/libraries/wutdevoptab/devoptab_fs_fsync.c
index 76bc8e5..d4eefb6 100644
--- a/libraries/wutdevoptab/devoptab_fs_fsync.c
+++ b/libraries/wutdevoptab/devoptab_fs_fsync.c
@@ -4,19 +4,22 @@ int
 __wut_fs_fsync(struct _reent *r,
                void *fd)
 {
-   FSStatus rc;
-   __wut_fs_file_t *file = (__wut_fs_file_t *)fd;
+   FSStatus status;
+   FSCmdBlock cmd;
+   __wut_fs_file_t *file;
 
-   // Set up command block
-   FSCmdBlock fsCmd;
-   FSInitCmdBlock(&fsCmd);
-
-   rc = FSFlushFile(__wut_devoptab_fs_client, &fsCmd, file->fd, -1);
-
-   if (rc >= 0) {
-      return 0;
+   if (!fd) {
+      r->_errno = EINVAL;
+      return -1;
    }
 
-   r->_errno = __wut_fs_translate_error(rc);
-   return -1;
+   FSInitCmdBlock(&cmd);
+   file = (__wut_fs_file_t *)fd;
+   status = FSFlushFile(__wut_devoptab_fs_client, &cmd, file->fd, -1);
+   if (status < 0) {
+      r->_errno = __wut_fs_translate_error(status);
+      return -1;
+   }
+
+   return 0;
 }
diff --git a/libraries/wutdevoptab/devoptab_fs_mkdir.c b/libraries/wutdevoptab/devoptab_fs_mkdir.c
index 9bdc331..d8fada3 100644
--- a/libraries/wutdevoptab/devoptab_fs_mkdir.c
+++ b/libraries/wutdevoptab/devoptab_fs_mkdir.c
@@ -5,34 +5,28 @@ __wut_fs_mkdir(struct _reent *r,
                const char *path,
                int mode)
 {
-   FSError  rc;
+   FSError status;
+   FSCmdBlock cmd;
+   char *fixedPath;
 
-   if (path == NULL) {
+   if (!path) {
+      r->_errno = EINVAL;
       return -1;
    }
 
-   char *path_fix = __wut_fs_fixpath(r, path);
-
-   if (!path_fix) {
-      r->_errno = ENOMEM;
+   fixedPath = __wut_fs_fixpath(r, path);
+   if (!fixedPath) {
       return -1;
    }
 
-   // Set up command block
-   FSCmdBlock fsCmd;
-   FSInitCmdBlock(&fsCmd);
-
    // TODO: Use mode to set directory attributes.
-   rc = FSMakeDir(__wut_devoptab_fs_client, &fsCmd, path_fix, -1);
-   free(path_fix);
-
-   if (rc == FS_ERROR_ALREADY_EXISTS) {
-      r->_errno = EEXIST;
+   FSInitCmdBlock(&cmd);
+   status = FSMakeDir(__wut_devoptab_fs_client, &cmd, fixedPath, -1);
+   free(fixedPath);
+   if (status < 0) {
+      r->_errno = __wut_fs_translate_error(status);
       return -1;
-   } else if(rc >= 0) {
-      return 0;
    }
 
-   r->_errno = __wut_fs_translate_error(rc);
-   return -1;
+   return 0;
 }
diff --git a/libraries/wutdevoptab/devoptab_fs_open.c b/libraries/wutdevoptab/devoptab_fs_open.c
index 813e219..ae92ed6 100644
--- a/libraries/wutdevoptab/devoptab_fs_open.c
+++ b/libraries/wutdevoptab/devoptab_fs_open.c
@@ -8,57 +8,52 @@ __wut_fs_open(struct _reent *r,
               int mode)
 {
    FSFileHandle fd;
-   FSStatus rc;
+   FSStatus status;
+   FSCmdBlock cmd;
+   const char *fsMode;
+   __wut_fs_file_t *file;
 
-   if (path == NULL) {
-      return -1;
-   }
-
-   char *path_fixed = __wut_fs_fixpath(r,path);
-   if (!path_fixed) {
-      r->_errno = ENOMEM;
-      return -1;
-   }
-
-   // Get pointer to our data
-   __wut_fs_file_t *file = (__wut_fs_file_t *)fileStruct;
-   const char *fs_mode;
-
-   // Map flags to open modes
-   if (flags == 0) {
-      fs_mode = "r";
-   } else if (flags == 2) {
-      fs_mode = "r+";
-   } else if (flags == 0x601) {
-      fs_mode = "w";
-   } else if(flags == 0x602) {
-      fs_mode = "w+";
-   } else if(flags == 0x209) {
-      fs_mode = "a";
-   } else if(flags == 0x20A) {
-      fs_mode = "a+";
-   } else {
-      free(path_fixed);
+   if (!fileStruct || !path) {
       r->_errno = EINVAL;
       return -1;
    }
 
-   // Set up command block
-   FSCmdBlock fsCmd;
-   FSInitCmdBlock(&fsCmd);
-
-   // Open the file
-   rc = FSOpenFile(__wut_devoptab_fs_client, &fsCmd, path_fixed, fs_mode, &fd, -1);
-
-   if (rc >= 0) {
-      file->fd = fd;
-      file->flags = (flags & (O_ACCMODE|O_APPEND|O_SYNC));
-      FSGetPosFile(__wut_devoptab_fs_client, &fsCmd, fd, &file->offset, -1);
-      free(path_fixed);
-      return 0;
+   // Map flags to open modes
+   if (flags == 0) {
+      fsMode = "r";
+   } else if (flags == 2) {
+      fsMode = "r+";
+   } else if (flags == 0x601) {
+      fsMode = "w";
+   } else if(flags == 0x602) {
+      fsMode = "w+";
+   } else if(flags == 0x209) {
+      fsMode = "a";
+   } else if(flags == 0x20A) {
+      fsMode = "a+";
+   } else {
+      r->_errno = EINVAL;
+      return -1;
    }
 
-   free(path_fixed);
-   r->_errno = __wut_fs_translate_error(rc);
-   return -1;
+   char *fixedPath = __wut_fs_fixpath(r,path);
+   if (!fixedPath) {
+      return -1;
+   }
+
+   // Open the file
+   FSInitCmdBlock(&cmd);
+   status = FSOpenFile(__wut_devoptab_fs_client, &cmd, fixedPath, fsMode, &fd,
+                       -1);
+   free(fixedPath);
+   if (status < 0) {
+      r->_errno = __wut_fs_translate_error(status);
+      return -1;
+   }
+
+   file = (__wut_fs_file_t *)fileStruct;
+   file->fd = fd;
+   file->flags = (flags & (O_ACCMODE|O_APPEND|O_SYNC));
+   FSGetPosFile(__wut_devoptab_fs_client, &cmd, fd, &file->offset, -1);
+   return 0;
 }
diff --git a/libraries/wutdevoptab/devoptab_fs_read.c b/libraries/wutdevoptab/devoptab_fs_read.c
index e17c886..33df4ea 100644
--- a/libraries/wutdevoptab/devoptab_fs_read.c
+++ b/libraries/wutdevoptab/devoptab_fs_read.c
@@ -6,9 +6,20 @@ __wut_fs_read(struct _reent *r,
               char *ptr,
               size_t len)
 {
-   FSStatus rc;
-   uint32_t bytes, bytesRead = 0;
-   __wut_fs_file_t *file = (__wut_fs_file_t *)fd;
+   FSStatus status;
+   FSCmdBlock cmd;
+   uint8_t *alignedReadBuffer;
+   uint32_t bytes, bytesRead;
+   __wut_fs_file_t *file;
+
+   if (!fd || !ptr) {
+      r->_errno = EINVAL;
+      return -1;
+   }
+
+   FSInitCmdBlock(&cmd);
+   file = (__wut_fs_file_t *)fd;
+   bytesRead = 0;
 
    // Check that the file was opened with read access
    if ((file->flags & O_ACCMODE) == O_WRONLY) {
@@ -16,55 +27,44 @@ __wut_fs_read(struct _reent *r,
       return -1;
    }
 
-   // Set up command block
-   FSCmdBlock fsCmd;
-   FSInitCmdBlock(&fsCmd);
-
-   FSStat fsstat;
-   rc = FSGetStatFile(__wut_devoptab_fs_client, &fsCmd, file->fd, &fsstat, -1);
-
-   if(rc < 0) {
-      r->_errno = __wut_fs_translate_error(rc);
-      return -1;
-   }
-
-   // Copy to internal buffer and read in chunks.
-   uint8_t *tmp_buffer = memalign(0x40, 8192);
-
-   while(len > 0) {
-      size_t toRead = len;
-
-      if (toRead > 8192) {
-         toRead = 8192;
-      }
+   // Copy to internal buffer due to alignment requirement and read in chunks.
+   alignedReadBuffer = memalign(0x40, 8192);
+   while (len > 0) {
+      size_t toRead = len > 8192 ? 8192 : len;
 
       // Write the data
-      rc = FSReadFile(__wut_devoptab_fs_client, &fsCmd, tmp_buffer, 1, toRead, file->fd, 0, -1);
-
-      if(rc <= 0)
-      {
-         free(tmp_buffer);
-
-         // Return partial transfer
-         if (bytesRead > 0) {
-            return bytesRead;
-         }
-
-         r->_errno = __wut_fs_translate_error(rc);
-         return -1;
-      } else {
-         bytes = rc;
+      status = FSReadFile(__wut_devoptab_fs_client, &cmd, alignedReadBuffer, 1,
+                          toRead, file->fd, 0, -1);
+      if (status <= 0) {
+         break;
       }
 
       // Copy to internal buffer
-      memcpy(ptr, tmp_buffer, bytes);
+      bytes = (uint32_t)status;
+      memcpy(ptr, alignedReadBuffer, bytes);
 
       file->offset += bytes;
       bytesRead    += bytes;
       ptr          += bytes;
       len          -= bytes;
+
+      if (bytes < toRead) {
+         // If we did not read the full requested toRead bytes then we reached
+         // the end of the file.
+         break;
+      }
+   }
+   free(alignedReadBuffer);
+
+   // Return partial read
+   if (bytesRead > 0) {
+      return bytesRead;
    }
 
-   free(tmp_buffer);
-   return bytesRead;
+   if (status < 0) {
+      r->_errno = __wut_fs_translate_error(status);
+      return -1;
+   }
+
+   return 0;
 }
diff --git a/libraries/wutdevoptab/devoptab_fs_rename.c b/libraries/wutdevoptab/devoptab_fs_rename.c
index 3d13715..bec601c 100644
--- a/libraries/wutdevoptab/devoptab_fs_rename.c
+++ b/libraries/wutdevoptab/devoptab_fs_rename.c
@@ -5,42 +5,36 @@ __wut_fs_rename(struct _reent *r,
                 const char *oldName,
                 const char *newName)
 {
-   FSStatus  rc;
+   FSStatus status;
+   FSCmdBlock cmd;
+   char *fixedOldPath, *fixedNewPath;
 
-   if (oldName == NULL) {
+   if (!oldName || !newName) {
+      r->_errno = EINVAL;
       return -1;
    }
 
-   if (newName == NULL) {
+   fixedOldPath = __wut_fs_fixpath(r, oldName);
+   if (!fixedOldPath) {
       return -1;
    }
 
-   char *path_old = __wut_fs_fixpath(r, oldName);
-
-   if (!path_old) {
-      r->_errno = ENOMEM;
+   fixedNewPath = __wut_fs_fixpath(r, newName);
+   if (!fixedNewPath) {
+      free(fixedOldPath);
       return -1;
    }
 
-   char *path_new = __wut_fs_fixpath(r, newName);
+   FSInitCmdBlock(&cmd);
+   status = FSRename(__wut_devoptab_fs_client, &cmd, fixedOldPath, fixedNewPath,
+                     -1);
+   free(fixedOldPath);
+   free(fixedNewPath);
 
-   if (!path_new) {
-      r->_errno = ENOMEM;
+   if (status < 0) {
+      r->_errno = __wut_fs_translate_error(status);
       return -1;
    }
 
-   // Set up command block
-   FSCmdBlock fsCmd;
-   FSInitCmdBlock(&fsCmd);
-
-   rc = FSRename(__wut_devoptab_fs_client, &fsCmd, path_old, path_new, -1);
-   free(path_old);
-   free(path_new);
-
-   if (rc >= 0) {
-      return 0;
-   }
-
-   r->_errno = __wut_fs_translate_error(rc);
-   return -1;
+   return 0;
 }
diff --git a/libraries/wutdevoptab/devoptab_fs_rmdir.c b/libraries/wutdevoptab/devoptab_fs_rmdir.c
index 32e98c1..da03e1e 100644
--- a/libraries/wutdevoptab/devoptab_fs_rmdir.c
+++ b/libraries/wutdevoptab/devoptab_fs_rmdir.c
@@ -4,30 +4,26 @@ int
 __wut_fs_rmdir(struct _reent *r,
                const char *name)
 {
-   FSStatus  rc;
+   FSStatus status;
+   FSCmdBlock cmd;
 
-   if (name == NULL) {
+   if (!name) {
+      r->_errno = EINVAL;
       return -1;
    }
 
-   char *path_fix = __wut_fs_fixpath(r, name);
-
-   if (!path_fix) {
-      r->_errno = ENOMEM;
+   char *fixedPath = __wut_fs_fixpath(r, name);
+   if (!fixedPath) {
       return -1;
    }
 
-   // Set up command block
-   FSCmdBlock fsCmd;
-   FSInitCmdBlock(&fsCmd);
-
-   rc = FSRemove(__wut_devoptab_fs_client, &fsCmd, path_fix, -1);
-   free(path_fix);
-
-   if (rc >= 0) {
-      return 0;
+   FSInitCmdBlock(&cmd);
+   status = FSRemove(__wut_devoptab_fs_client, &cmd, fixedPath, -1);
+   free(fixedPath);
+   if (status < 0) {
+      r->_errno = __wut_fs_translate_error(status);
+      return -1;
    }
 
-   r->_errno = __wut_fs_translate_error(rc);
-   return -1;
+   return 0;
 }
diff --git a/libraries/wutdevoptab/devoptab_fs_seek.c b/libraries/wutdevoptab/devoptab_fs_seek.c
index 740da48..3939d48 100644
--- a/libraries/wutdevoptab/devoptab_fs_seek.c
+++ b/libraries/wutdevoptab/devoptab_fs_seek.c
@@ -6,19 +6,23 @@ __wut_fs_seek(struct _reent *r,
               off_t pos,
               int whence)
 {
-   FSStatus rc;
+   FSStatus status;
+   FSCmdBlock cmd;
+   FSStat fsStat;
    uint64_t offset;
-   __wut_fs_file_t *file = (__wut_fs_file_t *)fd;
+   __wut_fs_file_t *file;
 
-   // Set up command block
-   FSCmdBlock fsCmd;
-   FSInitCmdBlock(&fsCmd);
+   if (!fd) {
+      r->_errno = EINVAL;
+      return -1;
+   }
 
-   FSStat fsstat;
-   rc = FSGetStatFile(__wut_devoptab_fs_client, &fsCmd, file->fd, &fsstat, -1);
-
-   if (rc < 0) {
-      r->_errno = __wut_fs_translate_error(rc);
+   FSInitCmdBlock(&cmd);
+   file = (__wut_fs_file_t *)fd;
+   status = FSGetStatFile(__wut_devoptab_fs_client, &cmd, file->fd, &fsStat,
+                          -1);
+   if (status < 0) {
+      r->_errno = __wut_fs_translate_error(status);
       return -1;
    }
 
@@ -36,7 +40,7 @@ __wut_fs_seek(struct _reent *r,
 
    // Set position relative to the end of the file
    case SEEK_END:
-      offset = fsstat.size;
+      offset = fsStat.size;
       break;
 
    // An invalid option was provided
@@ -54,10 +58,11 @@ __wut_fs_seek(struct _reent *r,
 
    // Update the current offset
    file->offset = offset + pos;
-   FSStatus result = FSSetPosFile(__wut_devoptab_fs_client, &fsCmd, file->fd, file->offset, -1);
-
-   if (result < 0) {
-      return result;
+   status = FSSetPosFile(__wut_devoptab_fs_client, &cmd, file->fd, file->offset,
+                         -1);
+   if (status < 0) {
+      r->_errno = __wut_fs_translate_error(status);
+      return -1;
    }
 
    return file->offset;
diff --git a/libraries/wutdevoptab/devoptab_fs_stat.c b/libraries/wutdevoptab/devoptab_fs_stat.c
index 472eeaf..3aaba53 100644
--- a/libraries/wutdevoptab/devoptab_fs_stat.c
+++ b/libraries/wutdevoptab/devoptab_fs_stat.c
@@ -2,41 +2,49 @@
 
 int
 __wut_fs_stat(struct _reent *r,
-              const char *file,
+              const char *path,
               struct stat *st)
 {
-   int      fd;
-   FSStatus rc;
+   int fd;
+   FSStatus status;
+   FSCmdBlock cmd;
 
-   if (file == NULL) {
+   if (!path || !st) {
+      r->_errno = EINVAL;
       return -1;
    }
 
-   // Set up command block
-   FSCmdBlock fsCmd;
-   FSInitCmdBlock(&fsCmd);
+   char *fixedPath = __wut_fs_fixpath(r, path);
+   if (!fixedPath)  {
+      return -1;
+   }
+
+   FSInitCmdBlock(&cmd);
 
    // First try open as file
-   rc = FSOpenFile(__wut_devoptab_fs_client, &fsCmd, file, "r", (FSFileHandle*)&fd, -1);
-
-   if (rc >= 0) {
+   status = FSOpenFile(__wut_devoptab_fs_client, &cmd, fixedPath, "r",
+                       (FSFileHandle*)&fd, -1);
+   if (status >= 0) {
       __wut_fs_file_t tmpfd = { .fd = fd };
-      rc = __wut_fs_fstat(r, &tmpfd, st);
-      FSCloseFile(__wut_devoptab_fs_client, &fsCmd, fd, -1);
-      return rc;
+      status = __wut_fs_fstat(r, &tmpfd, st);
+      FSCloseFile(__wut_devoptab_fs_client, &cmd, fd, -1);
+      free(fixedPath);
+      return status;
    }
 
    // File failed, so lets try open as directory
-   rc = FSOpenDir(__wut_devoptab_fs_client, &fsCmd, file, (FSDirectoryHandle*)&fd, -1);
-
-   if (rc >= 0) {
-      memset(st, 0, sizeof(struct stat));
-      st->st_nlink = 1;
-      st->st_mode = S_IFDIR | S_IRWXU | S_IRWXG | S_IRWXO;
-      FSCloseDir(__wut_devoptab_fs_client, &fsCmd, fd, -1);
-      return 0;
+   status = FSOpenDir(__wut_devoptab_fs_client, &cmd, fixedPath,
+                      (FSDirectoryHandle*)&fd, -1);
+   free(fixedPath);
+   if (status < 0) {
+      r->_errno = __wut_fs_translate_error(status);
+      return -1;
    }
 
-   r->_errno = __wut_fs_translate_error(rc);
-   return -1;
+   memset(st, 0, sizeof(struct stat));
+   st->st_nlink = 1;
+   st->st_mode = S_IFDIR | S_IRWXU | S_IRWXG | S_IRWXO;
+   FSCloseDir(__wut_devoptab_fs_client, &cmd, fd, -1);
+   free(fixedPath);
+   return 0;
 }
diff --git a/libraries/wutdevoptab/devoptab_fs_statvfs.c b/libraries/wutdevoptab/devoptab_fs_statvfs.c
index 6eddd2f..bc38cf4 100644
--- a/libraries/wutdevoptab/devoptab_fs_statvfs.c
+++ b/libraries/wutdevoptab/devoptab_fs_statvfs.c
@@ -5,17 +5,7 @@ __wut_fs_statvfs(struct _reent *r,
                  const char *path,
                  struct statvfs *buf)
 {
-   FSStatus rc;
-   char *path_fix = __wut_fs_fixpath(r, path);
-
-   if (!path_fix)  {
-      r->_errno = ENOMEM;
-      return -1;
-   }
-
    //TODO: FSGetFileSystemInfo
-
-   free(path_fix);
    r->_errno = ENOSYS;
    return -1;
 }
diff --git a/libraries/wutdevoptab/devoptab_fs_truncate.c b/libraries/wutdevoptab/devoptab_fs_truncate.c
index 5c546c9..dc49e86 100644
--- a/libraries/wutdevoptab/devoptab_fs_truncate.c
+++ b/libraries/wutdevoptab/devoptab_fs_truncate.c
@@ -5,32 +5,30 @@ __wut_fs_ftruncate(struct _reent *r,
                    void *fd,
                    off_t len)
 {
-   FSStatus rc;
-   __wut_fs_file_t *file = (__wut_fs_file_t *)fd;
+   FSStatus status;
+   FSCmdBlock cmd;
+   __wut_fs_file_t *file;
 
    // Make sure length is non-negative
-   if (len < 0) {
+   if (!fd || len < 0) {
       r->_errno = EINVAL;
       return -1;
    }
 
-   // Set up command block
-   FSCmdBlock fsCmd;
-   FSInitCmdBlock(&fsCmd);
-
    // Set the new file size
-   rc = FSSetPosFile(__wut_devoptab_fs_client, &fsCmd, file->fd, len, -1);
-
-   if (rc >= 0) {
-      return 0;
+   FSInitCmdBlock(&cmd);
+   file = (__wut_fs_file_t *)fd;
+   status = FSSetPosFile(__wut_devoptab_fs_client, &cmd, file->fd, len, -1);
+   if (status < 0) {
+      r->_errno = __wut_fs_translate_error(status);
+      return -1;
    }
 
-   rc = FSTruncateFile(__wut_devoptab_fs_client, &fsCmd, file->fd, -1);
-
-   if (rc >= 0) {
-      return 0;
+   status = FSTruncateFile(__wut_devoptab_fs_client, &cmd, file->fd, -1);
+   if (status < 0) {
+      r->_errno = __wut_fs_translate_error(status);
+      return -1;
    }
 
-   r->_errno = __wut_fs_translate_error(rc);
-   return -1;
+   return 0;
 }
diff --git a/libraries/wutdevoptab/devoptab_fs_unlink.c b/libraries/wutdevoptab/devoptab_fs_unlink.c
index ce5a40b..dc6f376 100644
--- a/libraries/wutdevoptab/devoptab_fs_unlink.c
+++ b/libraries/wutdevoptab/devoptab_fs_unlink.c
@@ -4,30 +4,27 @@ int
 __wut_fs_unlink(struct _reent *r,
                 const char *name)
 {
-   FSStatus  rc;
+   FSStatus status;
+   FSCmdBlock cmd;
+   char *fixedPath;
 
-   if (name == NULL) {
+   if (!name) {
+      r->_errno = EINVAL;
       return -1;
    }
 
-   char *path_fix = __wut_fs_fixpath(r, name);
-
-   if (!path_fix) {
-      r->_errno = ENOMEM;
+   fixedPath = __wut_fs_fixpath(r, name);
+   if (!fixedPath) {
       return -1;
    }
 
-   // Set up command block
-   FSCmdBlock fsCmd;
-   FSInitCmdBlock(&fsCmd);
-
-   rc = FSRemove(__wut_devoptab_fs_client, &fsCmd, path_fix, -1);
-   free(path_fix);
-
-   if (rc >= 0) {
-      return 0;
+   FSInitCmdBlock(&cmd);
+   status = FSRemove(__wut_devoptab_fs_client, &cmd, fixedPath, -1);
+   free(fixedPath);
+   if (status < 0) {
+      r->_errno = __wut_fs_translate_error(status);
+      return -1;
    }
 
-   r->_errno = __wut_fs_translate_error(rc);
-   return -1;
+   return 0;
 }
diff --git a/libraries/wutdevoptab/devoptab_fs_utils.c b/libraries/wutdevoptab/devoptab_fs_utils.c
index 7c126ad..02cf0ef 100644
--- a/libraries/wutdevoptab/devoptab_fs_utils.c
+++ b/libraries/wutdevoptab/devoptab_fs_utils.c
@@ -4,8 +4,15 @@ char *
 __wut_fs_fixpath(struct _reent *r,
                  const char *path)
 {
-   char *p = strchr(path, ':') + 1;
+   char *p;
+   char *fixedPath;
 
+   if (!path) {
+      r->_errno = EINVAL;
+      return NULL;
+   }
+
+   p = strchr(path, ':') + 1;
    if (!strchr(path, ':')) {
       p = (char*)path;
    }
@@ -15,21 +22,23 @@ __wut_fs_fixpath(struct _reent *r,
       return NULL;
    }
 
-   char *__fixedpath = memalign(0x40, PATH_MAX + 1);
-
-   if (__fixedpath == NULL) {
+   fixedPath = memalign(0x40, PATH_MAX + 1);
+   if (!fixedPath) {
+      r->_errno = ENOMEM;
       return NULL;
    }
 
    // cwd is handled by coreinit, so just strip the 'device:' if it exists
-   strcpy(__fixedpath, p);
-   return __fixedpath;
+   strcpy(fixedPath, p);
+   return fixedPath;
 }
 
 int
 __wut_fs_translate_error(FSStatus error)
 {
    switch (error) {
+   case FS_STATUS_END:
+      return ENOENT;
    case FS_STATUS_CANCELLED:
       return EINVAL;
    case FS_STATUS_EXISTS:
@@ -44,4 +53,3 @@ __wut_fs_translate_error(FSStatus error)
       return (int)error;
    }
 }
-
diff --git a/libraries/wutdevoptab/devoptab_fs_write.c b/libraries/wutdevoptab/devoptab_fs_write.c
index 62161f0..cffdb16 100644
--- a/libraries/wutdevoptab/devoptab_fs_write.c
+++ b/libraries/wutdevoptab/devoptab_fs_write.c
@@ -6,9 +6,20 @@ __wut_fs_write(struct _reent *r,
                const char *ptr,
                size_t len)
 {
-   FSStatus rc;
-   uint32_t bytes, bytesWritten = 0;
-   __wut_fs_file_t *file = (__wut_fs_file_t *)fd;
+   FSStatus status;
+   FSCmdBlock cmd;
+   uint8_t *alignedWriteBuffer;
+   uint32_t bytes, bytesWritten;
+   __wut_fs_file_t *file;
+
+   if (!fd || !ptr) {
+      r->_errno = EINVAL;
+      return -1;
+   }
+
+   FSInitCmdBlock(&cmd);
+   file = (__wut_fs_file_t *)fd;
+   bytesWritten = 0;
 
    // Check that the file was opened with write access
    if ((file->flags & O_ACCMODE) == O_RDONLY) {
@@ -16,46 +27,42 @@ __wut_fs_write(struct _reent *r,
       return -1;
    }
 
-   // Copy to internal buffer and write in chunks.
-   uint8_t *tmp_buffer = memalign(0x40, 8192);
-
-   while(len > 0) {
-      size_t toWrite = len;
-
-      if (toWrite > 8192) {
-         toWrite = 8192;
-      }
+   // Copy to internal buffer due to alignment requirement and write in chunks.
+   alignedWriteBuffer = memalign(0x40, 8192);
+   while (len > 0) {
+      size_t toWrite = len > 8192 ? 8192 : len;
 
       // Copy to internal buffer
-      memcpy(tmp_buffer, ptr, toWrite);
-
-      // Set up command block
-      FSCmdBlock fsCmd;
-      FSInitCmdBlock(&fsCmd);
+      memcpy(alignedWriteBuffer, ptr, toWrite);
 
       // Write the data
-      rc = FSWriteFile(__wut_devoptab_fs_client, &fsCmd, tmp_buffer, 1, toWrite, file->fd, 0, -1);
-
-      if (rc < 0) {
-         free(tmp_buffer);
-
-         // Return partial transfer
-         if (bytesWritten > 0) {
-            return bytesWritten;
-         }
-
-         r->_errno = __wut_fs_translate_error(rc);
-         return -1;
-      } else {
-         bytes = rc;
+      status = FSWriteFile(__wut_devoptab_fs_client, &cmd, alignedWriteBuffer,
+                           1, toWrite, file->fd, 0, -1);
+      if (status <= 0) {
+         break;
       }
 
+      bytes = (uint32_t)status;
       file->offset += bytes;
       bytesWritten += bytes;
       ptr          += bytes;
       len          -= bytes;
+
+      if (bytes < toWrite) {
+         break;
+      }
+   }
+   free(alignedWriteBuffer);
+
+   // Return partial write
+   if (bytesWritten > 0) {
+      return bytesWritten;
    }
 
-   free(tmp_buffer);
-   return bytesWritten;
+   if (status < 0) {
+      r->_errno = __wut_fs_translate_error(status);
+      return -1;
+   }
+
+   return 0;
 }