diff --git a/libtcc.c b/libtcc.c
index 6eea9a7..c6bc067 100644
--- a/libtcc.c
+++ b/libtcc.c
@@ -1154,7 +1154,7 @@ ST_FUNC int tcc_add_file_internal(TCCState *s1, const char *filename, int flags)
         goto the_end;
     }
 
-    if (!ext[0] || !PATHCMP(ext, "c")) {
+    if (!ext[0] || !PATHCMP(ext, "c") || !PATHCMP(ext, "i")) {
         /* C file assumed */
         ret = tcc_compile(s1);
         goto the_end;