diff --git a/playground/embedded_resources/main.c b/playground/embedded_resources/main.c
index 2d554bb1..a070fef5 100644
--- a/playground/embedded_resources/main.c
+++ b/playground/embedded_resources/main.c
@@ -10,7 +10,7 @@ int main()
 	size_t length = LDLEN(main_c);
 	uint8_t const * data = LDVAR(main_c);
 
-	printf("Data at %p, len %lu\n", data, length);
+	printf("Data at %p, len %zu\n", data, length);
 	printf("%s\n", data);
 
 	return 0;