diff --git a/document.c b/document.c
index 263b90a..f938adb 100644
--- a/document.c
+++ b/document.c
@@ -181,6 +181,10 @@ guess_type(const char* path)
     return NULL;
   }
 
+  if (uncertain == FALSE) {
+    return content_type;
+  }
+
   FILE* f = fopen(path, "r");
   if (f == NULL) {
     return NULL;