diff --git a/src/validation.c b/src/validation.c
index e732e5e..39617c2 100644
--- a/src/validation.c
+++ b/src/validation.c
@@ -12,6 +12,9 @@ static int validate_video_pixel_format(enum AVPixelFormat format)
 {
     switch (format) {
     // Still image formats
+    case AV_PIX_FMT_GRAY8:
+    case AV_PIX_FMT_GRAY10:
+    case AV_PIX_FMT_GRAY12:
     case AV_PIX_FMT_RGB8:
     case AV_PIX_FMT_RGB24:
     case AV_PIX_FMT_RGB32: