diff --git a/rules/common_settings.bzl b/rules/common_settings.bzl
index 9dca70e..e80ab09 100644
--- a/rules/common_settings.bzl
+++ b/rules/common_settings.bzl
@@ -24,10 +24,10 @@ https://docs.bazel.build/versions/master/skylark/config.html#user-defined-build-
 BuildSettingInfo = provider(
     doc = "A singleton provider that contains the raw value of a build setting",
     fields = {
-        "value": "The value of the build setting in the current configuration. "
-        + "This value may come from the command line or an upstream transition, "
-        + "or else it will be the build setting's default."
-    }
+        "value": "The value of the build setting in the current configuration. " +
+                 "This value may come from the command line or an upstream transition, " +
+                 "or else it will be the build setting's default.",
+    },
 )
 
 def _impl(ctx):
@@ -75,15 +75,16 @@ def _string_impl(ctx):
     if len(allowed_values) == 0 or value in ctx.attr.values:
         return BuildSettingInfo(value = value)
     else:
-      fail("Error setting "+ str(ctx.label) + ": invalid value '" + value + "'. Allowed values are " + str(allowed_values))
+        fail("Error setting " + str(ctx.label) + ": invalid value '" + value + "'. Allowed values are " + str(allowed_values))
 
 string_flag = rule(
     implementation = _string_impl,
     build_setting = config.string(flag = True),
     attrs = {
-        "values" : attr.string_list(
-            doc = "The list of allowed values for this setting. An error is raised if any other value is given."
-        )},
+        "values": attr.string_list(
+            doc = "The list of allowed values for this setting. An error is raised if any other value is given.",
+        ),
+    },
     doc = "A string-typed build setting that can be set on the command line",
 )
 
@@ -91,8 +92,9 @@ string_setting = rule(
     implementation = _string_impl,
     build_setting = config.string(),
     attrs = {
-    "values" : attr.string_list(
-        doc = "The list of allowed values for this setting. An error is raised if any other value is given."
-    )},
+        "values": attr.string_list(
+            doc = "The list of allowed values for this setting. An error is raised if any other value is given.",
+        ),
+    },
     doc = "A string-typed build setting that cannot be set on the command line",
 )