diff --git a/cores/libretro-ffmpeg/ffmpeg_core.c b/cores/libretro-ffmpeg/ffmpeg_core.c
index 7f7f1a13a8..32d41c6356 100644
--- a/cores/libretro-ffmpeg/ffmpeg_core.c
+++ b/cores/libretro-ffmpeg/ffmpeg_core.c
@@ -631,8 +631,12 @@ void CORE_PREFIX(retro_run)(void)
             {
 #ifndef HAVE_OPENGLES
                glBindBuffer(GL_PIXEL_UNPACK_BUFFER, frames[1].pbo);
+#ifdef __MACH__
+               data = (uint32_t*)glMapBuffer(GL_PIXEL_UNPACK_BUFFER, GL_WRITE_ONLY);
+#else
                data = (uint32_t*)glMapBufferRange(GL_PIXEL_UNPACK_BUFFER,
-                     0, media.width * media.height, GL_MAP_WRITE_BIT | GL_MAP_INVALIDATE_BUFFER_BIT);
+                     0, media.width * media.height * sizeof(uint32_t), GL_MAP_WRITE_BIT | GL_MAP_INVALIDATE_BUFFER_BIT);
+#endif
 #endif
 
                fifo_read(video_decode_fifo, data, media.width * media.height * sizeof(uint32_t));