diff --git a/portultra/events.cpp b/portultra/events.cpp
index 86ddeed..13de280 100644
--- a/portultra/events.cpp
+++ b/portultra/events.cpp
@@ -445,6 +445,18 @@ extern "C" void osViBlack(uint8_t active) {
     vi_black = active;
 }
 
+extern "C" void osViSetXScale(float scale) {
+    if (scale != 1.0f) {
+        assert(false);
+    }
+}
+
+extern "C" void osViSetYScale(float scale) {
+    if (scale != 1.0f) {
+        assert(false);
+    }
+}
+
 extern "C" PTR(void) osViGetNextFramebuffer() {
     return events_context.vi.next_buffer;
 }
diff --git a/portultra/ultra64.h b/portultra/ultra64.h
index 8777dbd..c9122cc 100644
--- a/portultra/ultra64.h
+++ b/portultra/ultra64.h
@@ -237,6 +237,8 @@ void osViSwapBuffer(RDRAM_ARG PTR(void) frameBufPtr);
 void osViSetMode(RDRAM_ARG PTR(OSViMode));
 void osViSetSpecialFeatures(uint32_t func);
 void osViBlack(uint8_t active);
+void osViSetXScale(float scale);
+void osViSetYScale(float scale);
 PTR(void) osViGetNextFramebuffer();
 PTR(void) osViGetCurrentFramebuffer();
 u32 osGetCount();
diff --git a/src/vi.cpp b/src/vi.cpp
index d7595d9..4301d11 100644
--- a/src/vi.cpp
+++ b/src/vi.cpp
@@ -2,11 +2,11 @@
 #include "recomp.h"
 
 extern "C" void osViSetYScale_recomp(uint8_t* rdram, recomp_context * ctx) {
-    assert(false);
+    osViSetYScale(ctx->f12.fl);
 }
 
 extern "C" void osViSetXScale_recomp(uint8_t* rdram, recomp_context * ctx) {
-    assert(false);
+    osViSetXScale(ctx->f12.fl);
 }
 
 extern "C" void osCreateViManager_recomp(uint8_t* rdram, recomp_context* ctx) {