diff --git a/OEP4Sample/OEP4Sample.py b/OEP4Sample/OEP4Sample.py
index 2023603..068b374 100644
--- a/OEP4Sample/OEP4Sample.py
+++ b/OEP4Sample/OEP4Sample.py
@@ -120,14 +120,14 @@ def decimals():
     """
     :return: the decimals of the token
     """
-    return DECIMALS
+    return DECIMALS + 0
 
 
 def totalSupply():
     """
     :return: the total supply of the token
     """
-    return Get(ctx, SUPPLY_KEY)
+    return Get(ctx, SUPPLY_KEY) + 0
 
 
 def balanceOf(account):
@@ -137,7 +137,7 @@ def balanceOf(account):
     """
     if len(account) != 20:
         raise Exception("address length error")
-    return Get(ctx,concat(BALANCE_PREFIX,account))
+    return Get(ctx,concat(BALANCE_PREFIX,account)) + 0
 
 
 def transfer(from_acct,to_acct,amount):
@@ -265,4 +265,4 @@ def allowance(owner,spender):
     :return: the allowed amount of tokens
     """
     key = concat(concat(APPROVE_PREFIX,owner),spender)
-    return Get(ctx,key)
\ No newline at end of file
+    return Get(ctx,key) + 0
diff --git a/OEP4Sample/OEP4Sample_compiler2.0.py b/OEP4Sample/OEP4Sample_compiler2.0.py
index 7d559f1..27bfd04 100644
--- a/OEP4Sample/OEP4Sample_compiler2.0.py
+++ b/OEP4Sample/OEP4Sample_compiler2.0.py
@@ -129,7 +129,7 @@ def totalSupply():
     """
     :return: the total supply of the token
     """
-    return Get(ctx, SUPPLY_KEY)
+    return Get(ctx, SUPPLY_KEY) + 0
 
 
 def balanceOf(account):
@@ -139,7 +139,7 @@ def balanceOf(account):
     """
     if len(account) != 20:
         raise Exception("address length error")
-    return Get(ctx,concat(BALANCE_PREFIX,account))
+    return Get(ctx,concat(BALANCE_PREFIX,account)) + 0
 
 
 def transfer(from_acct,to_acct,amount):
@@ -267,4 +267,4 @@ def allowance(owner,spender):
     :return: the allowed amount of tokens
     """
     key = concat(concat(APPROVE_PREFIX,owner),spender)
-    return Get(ctx,key)
\ No newline at end of file
+    return Get(ctx,key) + 0
\ No newline at end of file