diff --git a/libavfilter/drawutils.c b/libavfilter/drawutils.c
index 3a1abbd95a..5a82b10cd6 100644
--- a/libavfilter/drawutils.c
+++ b/libavfilter/drawutils.c
@@ -21,6 +21,7 @@
 
 #include <string.h>
 
+#include "libavutil/avassert.h"
 #include "libavutil/avutil.h"
 #include "libavutil/colorspace.h"
 #include "libavutil/mem.h"
@@ -66,7 +67,11 @@ int ff_fill_line_with_color(uint8_t *line[4], int pixel_step[4], int w, uint8_t
     uint8_t rgba_map[4] = {0};
     int i;
     const AVPixFmtDescriptor *pix_desc = av_pix_fmt_desc_get(pix_fmt);
-    int hsub = pix_desc->log2_chroma_w;
+    int hsub;
+
+    av_assert0(pix_desc);
+
+    hsub = pix_desc->log2_chroma_w;
 
     *is_packed_rgba = ff_fill_rgba_map(rgba_map, pix_fmt) >= 0;