diff --git a/buildifier/def.bzl b/buildifier/def.bzl
index 0f2db20db..aa7a6b03b 100644
--- a/buildifier/def.bzl
+++ b/buildifier/def.bzl
@@ -21,7 +21,7 @@ def _buildifier_impl(ctx):
 
     exclude_patterns_str = ""
     if ctx.attr.exclude_patterns:
-        exclude_patterns = ["\! -path %s" % shell.quote(pattern) for pattern in ctx.attr.exclude_patterns]
+        exclude_patterns = ["\\! -path %s" % shell.quote(pattern) for pattern in ctx.attr.exclude_patterns]
         exclude_patterns_str = " ".join(exclude_patterns)
 
     out_file = ctx.actions.declare_file(ctx.label.name + ".bash")