diff --git a/libavfilter/formats.c b/libavfilter/formats.c
index 58593fcce0..4a23c2f1b3 100644
--- a/libavfilter/formats.c
+++ b/libavfilter/formats.c
@@ -99,7 +99,7 @@ int avfilter_add_format(AVFilterFormats **avff, int fmt)
         return AVERROR(ENOMEM);
 
     fmts = av_realloc((*avff)->formats,
-                      sizeof((*avff)->formats) * ((*avff)->format_count+1));
+                      sizeof(*(*avff)->formats) * ((*avff)->format_count+1));
     if (!fmts)
         return AVERROR(ENOMEM);