diff --git a/constants.go b/constants.go
index b7e90ff..97a2750 100644
--- a/constants.go
+++ b/constants.go
@@ -1968,16 +1968,15 @@ func NewAssetClass(s string) (assetClass, error) {
 type mfType uint
 
 const (
-	MfTypeOpen mfType = 1 + iota
-	MfTypeEnd
+	MfTypeOpenEnd mfType = 1 + iota
 	MfTypeCloseEnd
 	MfTypeOther
 )
 
-var mfTypes = [...]string{"OPEN", "END", "CLOSEEND", "OTHER"}
+var mfTypes = [...]string{"OPENEND", "CLOSEEND", "OTHER"}
 
 func (e mfType) Valid() bool {
-	return e >= MfTypeOpen && e <= MfTypeOther
+	return e >= MfTypeOpenEnd && e <= MfTypeOther
 }
 
 func (e mfType) String() string {
diff --git a/generate_constants.py b/generate_constants.py
index bec0c01..928c4cf 100755
--- a/generate_constants.py
+++ b/generate_constants.py
@@ -39,7 +39,7 @@ enums = {
     "CouponFreq": ["Monthly", "Quarterly", "Semiannual", "Annual", "Other"],
     "CallType": ["Call", "Put", "Prefund", "Maturity"],
     "AssetClass": ["DomesticBond", "IntlBond", "LargeStock", "SmallStock", "IntlStock", "MoneyMrkt", "Other"],
-    "MfType": ["Open", "End", "CloseEnd", "Other"],
+    "MfType": ["OpenEnd", "CloseEnd", "Other"],
     "OptType": ["Put", "Call"],
     "StockType": ["Common", "Preferred", "Convertible", "Other"],
     "OfxSec": ["None", "Type 1"],