diff --git a/graphql/utils/ast_from_value.py b/graphql/utils/ast_from_value.py
index 6773423b..05da84a7 100644
--- a/graphql/utils/ast_from_value.py
+++ b/graphql/utils/ast_from_value.py
@@ -45,9 +45,10 @@ def ast_from_value(value, type=None):
         return ast.FloatValue(string_num)
 
     if isinstance(value, string_types):
-        if isinstance(type, GraphQLEnumType) and re.match(
-            r"^[_a-zA-Z][_a-zA-Z0-9]*$", value
-        ):
+        if (
+            isinstance(type, GraphQLEnumType)
+            or ("type" in dir(type) and isinstance(type.type, GraphQLEnumType))
+        ) and re.match(r"^[_a-zA-Z][_a-zA-Z0-9]*$", value):
             return ast.EnumValue(value)
 
         return ast.StringValue(json.dumps(value)[1:-1])