diff --git a/tools/migration/crosstool_to_starlark_lib.go b/tools/migration/crosstool_to_starlark_lib.go
index 77b7565..675ab1c 100644
--- a/tools/migration/crosstool_to_starlark_lib.go
+++ b/tools/migration/crosstool_to_starlark_lib.go
@@ -304,7 +304,7 @@
 			fmt.Sprintf(`"compiler": attr.string(values=["%s"]),`,
 				strings.Join(compilerValues, "\", \"")))
 	}
-	return fmt.Sprintf(`cc_toolchain_config_rule =  rule(
+	return fmt.Sprintf(`cc_toolchain_config =  rule(
     implementation = _impl,
     attrs = {
         %s
@@ -1074,6 +1074,11 @@
 				fmt.Sprintf(
 					"%selse:\n%sfail(\"Unreachable\")\n",
 					getTabs(depth), getTabs(depth+1)))
+		} else {
+			b.WriteString(
+				fmt.Sprintf(
+					"%selse:\n%s%s = None\n",
+					getTabs(depth), getTabs(depth+1), field))
 		}
 	}
 	b.WriteString("\n")
diff --git a/tools/migration/crosstool_to_starlark_lib_test.go b/tools/migration/crosstool_to_starlark_lib_test.go
index bcbc997..459cb3a 100644
--- a/tools/migration/crosstool_to_starlark_lib_test.go
+++ b/tools/migration/crosstool_to_starlark_lib_test.go
@@ -1080,7 +1080,7 @@
 	}
 }
 
-func TestNoFailUnreachableInFeaturesAndActionConfigsDeclaration(t *testing.T) {
+func TestFeaturesAndActionConfigsSetToNoneWhenAllOptionsAreExausted(t *testing.T) {
 	toolchainFeatureAEnabled := getCToolchain("1", "cpuA", "compilerA",
 		[]string{getFeature([]string{"name: 'A'", "enabled: true"})},
 	)
@@ -1118,8 +1118,9 @@
         a_feature = feature(name = "A")
     elif (ctx.attr.cpu == "cpuA" and ctx.attr.compiler == "compilerA"):
         a_feature = feature(name = "A", enabled = True)
-
-` /* empty line after the elif means there's no else statement */},
+    else:
+        a_feature = None
+`},
 		{field: "action_config",
 			toolchains: []string{
 				toolchainActionConfigAEnabled, toolchainActionConfigADisabled, toolchainWithoutActionConfigA},
@@ -1128,8 +1129,9 @@
         a_action = action_config(action_name = "A")
     elif (ctx.attr.cpu == "cpuA" and ctx.attr.compiler == "compilerD"):
         a_action = action_config(action_name = "A", enabled = True)
-
-` /* empty line after the elif means there's no else statement */ },
+    else:
+        a_action = None
+`},
 	}
 
 	for _, tc := range testCases {