diff --git a/libavfilter/vf_psnr.c b/libavfilter/vf_psnr.c
index 3744579d71..1bcdd7de5c 100644
--- a/libavfilter/vf_psnr.c
+++ b/libavfilter/vf_psnr.c
@@ -91,7 +91,7 @@ void compute_images_mse(PSNRContext *s,
         const uint8_t *ref_line = ref_data[c];
         const int ref_linesize = ref_linesizes[c];
         const int main_linesize = main_linesizes[c];
-        int m = 0;
+        uint64_t m = 0;
 
         for (i = 0; i < outh; i++) {
             for (j = 0; j < outw; j++)