diff --git a/.cirrus.yml b/.cirrus.yml
index 725c836380..3015126cb2 100644
--- a/.cirrus.yml
+++ b/.cirrus.yml
@@ -11,4 +11,4 @@ task:
     ##.github/workflows/freebsd_build_tcc.sh
     ##tcc -v -v
     echo 'Build cmd/tools/fast'
-    cd cmd/tools/fast && ../../../v fast.v ## && ./fast
+    cd cmd/tools/fast && ../../../v fast.v && ./fast -clang
diff --git a/cmd/tools/fast/fast.v b/cmd/tools/fast/fast.v
index 2c1bc06e8d..a182b4ff24 100644
--- a/cmd/tools/fast/fast.v
+++ b/cmd/tools/fast/fast.v
@@ -65,6 +65,9 @@ fn main() {
 			tcc_path = 'clang'
 		}
 	}
+	if os.args.contains('-clang') {
+		tcc_path = 'clang'
+	}
 	diff2 := measure('$vdir/vprod $voptions -cc $tcc_path -o v2 cmd/v', 'v2')
 	diff3 := 0 // measure('$vdir/vprod -native $vdir/cmd/tools/1mil.v', 'native 1mil')
 	diff4 := measure('$vdir/vprod -usecache $voptions -cc clang examples/hello_world.v',