diff --git a/kitty/parser.c b/kitty/parser.c
index 9ab1616dc..9d538e53b 100644
--- a/kitty/parser.c
+++ b/kitty/parser.c
@@ -15,7 +15,7 @@ static unsigned int pow10[10] = {
 static inline unsigned int 
 utoi(uint32_t *buf, unsigned int sz) {
     unsigned int ans = 0;
-    if (sz < 10) {
+    if (sz < sizeof(pow10)/sizeof(pow10[10])) {
         for (int i = sz-1, j=0; i >=0; i--, j++) {
             ans += (buf[i] - '0') * pow10[j];
         }