Do not regard rules which start with dot as the first rule
diff --git a/exec.go b/exec.go
index 87da560..2092cb3 100644
--- a/exec.go
+++ b/exec.go
@@ -402,7 +402,7 @@
 			ex.rules[output] = r
 		} else {
 			ex.rules[output] = rule
-			if ex.firstRule == nil && !isSuffixRule {
+			if ex.firstRule == nil && !strings.HasPrefix(output, ".") {
 				ex.firstRule = rule
 			}
 		}