diff --git a/common/frame.c b/common/frame.c
index 70bcf8a..becdaad 100644
--- a/common/frame.c
+++ b/common/frame.c
@@ -844,41 +844,32 @@ void x264_frame_cond_wait( x264_frame_t *frame, int i_lines_completed )
     x264_pthread_mutex_unlock( &frame->mutex );
 }
 
-void x264_frame_size_estimated_set( x264_t *h, int bits )
-{
-    x264_pthread_mutex_lock( &h->fenc->mutex );
-    x264_ratecontrol_set_estimated_size(h, bits);
-    x264_pthread_mutex_unlock( &h->fenc->mutex );
-}
-
-int x264_frame_size_estimated_get( x264_t const *h)
-{
-    int size;
-    x264_pthread_mutex_lock( &h->fenc->mutex );
-    size = x264_ratecontrol_get_estimated_size(h);
-    x264_pthread_mutex_unlock( &h->fenc->mutex );
-    return size;
-}
-
 #else
 void x264_frame_cond_broadcast( x264_frame_t *frame, int i_lines_completed )
 {}
 void x264_frame_cond_wait( x264_frame_t *frame, int i_lines_completed )
 {}
 
+#endif
+
+extern void x264_ratecontrol_set_estimated_size( x264_t *, int bits );
+extern int x264_ratecontrol_get_estimated_size( x264_t const *);
+
 void x264_frame_size_estimated_set( x264_t *h, int bits )
 {
+    x264_pthread_mutex_lock( &h->fenc->mutex );
     x264_ratecontrol_set_estimated_size(h, bits);
+    x264_pthread_mutex_unlock( &h->fenc->mutex );
 }
 
 int x264_frame_size_estimated_get( x264_t const *h)
 {
     int size;
-    size = x264_ratecontrol_set_estimated_size(h);
+    x264_pthread_mutex_lock( &h->fenc->mutex );
+    size = x264_ratecontrol_get_estimated_size(h);
+    x264_pthread_mutex_unlock( &h->fenc->mutex );
     return size;
 }
-#endif
-
 
 /* list operators */