diff --git a/mongoose.c b/mongoose.c
index 99a6d017..d4dc69d7 100644
--- a/mongoose.c
+++ b/mongoose.c
@@ -4212,7 +4212,7 @@ int mg_asprintf(char **buf, size_t size, const char *fmt, ...) {
 }
 
 int64_t mg_to64(struct mg_str str) {
-  int64_t result = 0, neg = 1, max = 922337203685477580 /* INT64_MAX / 10 */;
+  int64_t result = 0, neg = 1, max = 922337203685477570 /* INT64_MAX/10-10 */;
   size_t i = 0;
   while (i < str.len && (str.ptr[i] == ' ' || str.ptr[i] == '\t')) i++;
   if (i < str.len && str.ptr[i] == '-') neg = -1, i++;
diff --git a/src/util.c b/src/util.c
index d4f6c258..61c9e087 100644
--- a/src/util.c
+++ b/src/util.c
@@ -262,7 +262,7 @@ int mg_asprintf(char **buf, size_t size, const char *fmt, ...) {
 }
 
 int64_t mg_to64(struct mg_str str) {
-  int64_t result = 0, neg = 1, max = 922337203685477580 /* INT64_MAX / 10 */;
+  int64_t result = 0, neg = 1, max = 922337203685477570 /* INT64_MAX/10-10 */;
   size_t i = 0;
   while (i < str.len && (str.ptr[i] == ' ' || str.ptr[i] == '\t')) i++;
   if (i < str.len && str.ptr[i] == '-') neg = -1, i++;