Fixed warning building with Visual Studio
diff --git a/src/SDL_assert.c b/src/SDL_assert.c
index 04299a9..02cd6b3 100644
--- a/src/SDL_assert.c
+++ b/src/SDL_assert.c
@@ -182,7 +182,7 @@ SDL_PromptAssertion(const SDL_assert_data *data, void *userdata)
len = SDL_RenderAssertMessage(message, buf_len, data);
/* .. and if it didn't, try to allocate as much room as we actually need. */
- if (len >= buf_len) {
+ if (len >= (int)buf_len) {
if (SDL_size_add_overflow(len, 1, &buf_len) == 0) {
message = (char *)SDL_malloc(buf_len);
if (message) {