diff --git a/core/cd_hw/libchdr/deps/libFLAC/include/share/compat.h b/core/cd_hw/libchdr/deps/libFLAC/include/share/compat.h
index 4f33bc1..dcb9350 100644
--- a/core/cd_hw/libchdr/deps/libFLAC/include/share/compat.h
+++ b/core/cd_hw/libchdr/deps/libFLAC/include/share/compat.h
@@ -197,6 +197,7 @@
  * This function wraps the MS version to behave more like the ISO version.
  */
 #include <stdarg.h>
+#include <stddef.h>
 #ifdef __cplusplus
 extern "C" {
 #endif