diff --git a/src/arch/MovieTexture/MovieTexture_FFMpeg.cpp b/src/arch/MovieTexture/MovieTexture_FFMpeg.cpp
index 1f5e0f0be7..e7cf2077ad 100644
--- a/src/arch/MovieTexture/MovieTexture_FFMpeg.cpp
+++ b/src/arch/MovieTexture/MovieTexture_FFMpeg.cpp
@@ -685,7 +685,11 @@ int URLRageFile_read( avcodec::URLContext *h, unsigned char *buf, int size )
 	return f->Read( buf, size );
 }
 
-int URLRageFile_write( avcodec::URLContext *h, const unsigned char *buf, int size )
+#if defined(MACOSX)
+	int URLRageFile_write( avcodec::URLContext *h, unsigned char *buf, int size )
+#else
+	int URLRageFile_write( avcodec::URLContext *h, const unsigned char *buf, int size )
+#end
 {
 	RageFileBasic *f = (RageFileBasic *) h->priv_data;
 	return f->Write( buf, size );