diff --git a/apps/common/field/common.py b/apps/common/field/common.py
index a97469891..3d6c95f11 100644
--- a/apps/common/field/common.py
+++ b/apps/common/field/common.py
@@ -27,7 +27,7 @@ class FunctionField(serializers.Field):
 
     def to_internal_value(self, data):
         if not callable(data):
-            self.fail('不是一個函數', value=data)
+            self.fail('不是一个函數', value=data)
         return data
 
     def to_representation(self, value):