diff --git a/src/common/vector.c b/src/common/vector.c
index 5b91f11d..383bf8b5 100644
--- a/src/common/vector.c
+++ b/src/common/vector.c
@@ -31,7 +31,7 @@ void c11_vector__reserve(c11_vector* self, int capacity){
     if(capacity < 4) capacity = 4;
     if(capacity <= self->capacity) return;
     // self->elem_size * capacity may overflow
-    self->data = realloc(self->data, self->elem_size * (size_t)capacity);
+    self->data = realloc(self->data, (size_t)self->elem_size * (size_t)capacity);
     self->capacity = capacity;
 }