diff --git a/libmpcodecs/ad_twin.c b/libmpcodecs/ad_twin.c
index 5f38dd0c4b..03122ce6ad 100644
--- a/libmpcodecs/ad_twin.c
+++ b/libmpcodecs/ad_twin.c
@@ -184,7 +184,7 @@ void uninit(sh_audio_t *sh)
   FreeLibrary(vqf_dll);
 }
 
-int control(sh_audio_t *sh_audio,int cmd,void* arg, ...)
+static int control(sh_audio_t *sh_audio,int cmd,void* arg, ...)
 {
   switch(cmd) {
       case ADCTRL_QUERY_FORMAT:
diff --git a/libmpcodecs/vf_screenshot.c b/libmpcodecs/vf_screenshot.c
index 93fef3e186..7543d45e34 100644
--- a/libmpcodecs/vf_screenshot.c
+++ b/libmpcodecs/vf_screenshot.c
@@ -204,7 +204,7 @@ static int put_image(struct vf_instance_s* vf, mp_image_t *mpi, double pts)
     return vf_next_put_image(vf, dmpi, pts);
 }
 
-int control (vf_instance_t *vf, int request, void *data)
+static int control (vf_instance_t *vf, int request, void *data)
 {
     /** data contains an integer argument
      * 0: take screenshot with the next frame