diff --git a/executor/executor.go b/executor/executor.go
index 8c72672453..9f97b24491 100644
--- a/executor/executor.go
+++ b/executor/executor.go
@@ -60,11 +60,11 @@ var (
 
 // Error codes.
 const (
-	CodeUnknownPlan terror.ErrCode = iota
-	CodePrepareMulti
-	CodeStmtNotFound
-	CodeSchemaChanged
-	CodeWrongParamCount
+	CodeUnknownPlan     terror.ErrCode = 1
+	CodePrepareMulti    terror.ErrCode = 2
+	CodeStmtNotFound    terror.ErrCode = 3
+	CodeSchemaChanged   terror.ErrCode = 4
+	CodeWrongParamCount terror.ErrCode = 5
 )
 
 // Row represents a record row.
diff --git a/kv/error.go b/kv/error.go
index 208411ea94..831c01c227 100644
--- a/kv/error.go
+++ b/kv/error.go
@@ -25,8 +25,8 @@ import (
 // KV error codes.
 const (
 	CodeIncompatibleDBFormat terror.ErrCode = 1
-	CodeNoDataForHandle                     = 2
-	CodeKeyExists                           = 3
+	CodeNoDataForHandle      terror.ErrCode = 2
+	CodeKeyExists            terror.ErrCode = 3
 )
 
 var (
diff --git a/optimizer/evaluator/evaluator.go b/optimizer/evaluator/evaluator.go
index 8bc1c16e78..f4555c188f 100644
--- a/optimizer/evaluator/evaluator.go
+++ b/optimizer/evaluator/evaluator.go
@@ -39,7 +39,7 @@ var (
 
 // Error codes.
 const (
-	CodeInvalidOperation terror.ErrCode = iota
+	CodeInvalidOperation terror.ErrCode = 1
 )
 
 // Eval evaluates an expression to a value.
diff --git a/optimizer/plan/planbuilder.go b/optimizer/plan/planbuilder.go
index ab33dee9cd..fba6f852cc 100644
--- a/optimizer/plan/planbuilder.go
+++ b/optimizer/plan/planbuilder.go
@@ -34,7 +34,7 @@ var (
 
 // Error codes.
 const (
-	CodeUnsupportedType = iota
+	CodeUnsupportedType terror.ErrCode = 1
 )
 
 // BuildPlan builds a plan from a node.
diff --git a/parser/yy_parser.go b/parser/yy_parser.go
index 790e2367ac..36ed8b8c5a 100644
--- a/parser/yy_parser.go
+++ b/parser/yy_parser.go
@@ -27,7 +27,7 @@ var (
 
 // Error codes.
 const (
-	CodeSyntaxErr terror.ErrCode = iota + 1
+	CodeSyntaxErr terror.ErrCode = 1
 )
 
 // Parse parses a query string to raw ast.StmtNode.
diff --git a/sessionctx/variable/sysvar.go b/sessionctx/variable/sysvar.go
index 2b5a61106a..1f281ce19c 100644
--- a/sessionctx/variable/sysvar.go
+++ b/sessionctx/variable/sysvar.go
@@ -57,7 +57,7 @@ func GetSysVar(name string) *SysVar {
 // Variable error codes.
 const (
 	CodeUnknownStatusVar terror.ErrCode = 1
-	CodeUnknownSystemVar                = 1193
+	CodeUnknownSystemVar terror.ErrCode = 1193
 )
 
 // Variable errors