diff --git a/libswscale/tests/swscale.c b/libswscale/tests/swscale.c
index e72c4c3306..cb731f6211 100644
--- a/libswscale/tests/swscale.c
+++ b/libswscale/tests/swscale.c
@@ -312,10 +312,10 @@ static int fileTest(const uint8_t * const ref[4], int refStride[4],
     while (fgets(buf, sizeof(buf), fp)) {
         struct Results r;
         enum AVPixelFormat srcFormat;
-        char srcStr[12];
+        char srcStr[13];
         int srcW = 0, srcH = 0;
         enum AVPixelFormat dstFormat;
-        char dstStr[12];
+        char dstStr[13];
         int dstW = 0, dstH = 0;
         int flags;
         int ret;