diff --git a/assembler/src/main.c b/assembler/src/main.c
index 91072938..28cca232 100644
--- a/assembler/src/main.c
+++ b/assembler/src/main.c
@@ -275,6 +275,9 @@ int main(int argc, char **argv)
 
 	err = yyparse();
 
+	if (yyin)
+		fclose(yyin);
+
 	if (err || errors)
 		exit (1);