diff --git a/autistdraw.c b/autistdraw.c
index 45f63a5..2d86f63 100644
--- a/autistdraw.c
+++ b/autistdraw.c
@@ -836,7 +836,7 @@ load (app_context_t *app)
 	if (!bitmap)
 		goto error;
 
-	char c;
+	int c;
 	uint8_t pixel = 0;
 	bool have_nibble = false;
 	size_t loaded = 0;