diff --git a/openrtb_ext/convert_up.go b/openrtb_ext/convert_up.go
index 2cfb07fb07..cfc9259b20 100644
--- a/openrtb_ext/convert_up.go
+++ b/openrtb_ext/convert_up.go
@@ -168,7 +168,7 @@ func moveRewardedFromPrebidExtTo26(i *ImpWrapper) {
 	// read and clear prebid ext
 	impExt, _ := i.GetImpExt()
 	rwddPrebidExt := (*int8)(nil)
-	if p := impExt.GetPrebid(); p != nil {
+	if p := impExt.GetPrebid(); p != nil && p.IsRewardedInventory != nil {
 		rwddPrebidExt = p.IsRewardedInventory
 		p.IsRewardedInventory = nil
 		impExt.SetPrebid(p)
diff --git a/openrtb_ext/convert_up_test.go b/openrtb_ext/convert_up_test.go
index f83b85be89..2b5c230389 100644
--- a/openrtb_ext/convert_up_test.go
+++ b/openrtb_ext/convert_up_test.go
@@ -417,12 +417,12 @@ func TestMoveRewardedFromPrebidExtTo26(t *testing.T) {
 		{
 			description: "Not Present - Null Prebid Ext",
 			givenImp:    openrtb2.Imp{Ext: json.RawMessage(`{"prebid":null}`)},
-			expectedImp: openrtb2.Imp{}, // empty prebid object pruned by RebuildImp
+			expectedImp: openrtb2.Imp{Ext: json.RawMessage(`{"prebid":null}`)},
 		},
 		{
 			description: "Not Present - Empty Prebid Ext",
 			givenImp:    openrtb2.Imp{Ext: json.RawMessage(`{"prebid":{}}`)},
-			expectedImp: openrtb2.Imp{}, // empty prebid object pruned by RebuildImp
+			expectedImp: openrtb2.Imp{Ext: json.RawMessage(`{"prebid":{}}`)},
 		},
 		{
 			description: "Prebid Ext Migrated To 2.6",
diff --git a/openrtb_ext/imp.go b/openrtb_ext/imp.go
index e02cfadc59..85be312454 100644
--- a/openrtb_ext/imp.go
+++ b/openrtb_ext/imp.go
@@ -43,6 +43,8 @@ type ExtImpPrebid struct {
 
 	Options *Options `json:"options,omitempty"`
 
+	AdUnitCode string `json:"adunitcode,omitempty"`
+
 	Passthrough json.RawMessage `json:"passthrough,omitempty"`
 
 	Floors *ExtImpPrebidFloors `json:"floors,omitempty"`
diff --git a/openrtb_ext/request_wrapper_test.go b/openrtb_ext/request_wrapper_test.go
index 650a1efbe9..73851238d0 100644
--- a/openrtb_ext/request_wrapper_test.go
+++ b/openrtb_ext/request_wrapper_test.go
@@ -189,8 +189,10 @@ func TestUserExt(t *testing.T) {
 
 func TestRebuildImp(t *testing.T) {
 	var (
-		prebid     = &ExtImpPrebid{IsRewardedInventory: openrtb2.Int8Ptr(1)}
-		prebidJson = json.RawMessage(`{"prebid":{"is_rewarded_inventory":1}}`)
+		prebid                   = &ExtImpPrebid{IsRewardedInventory: openrtb2.Int8Ptr(1)}
+		prebidJson               = json.RawMessage(`{"prebid":{"is_rewarded_inventory":1}}`)
+		prebidWithAdunitCode     = &ExtImpPrebid{AdUnitCode: "adunitcode"}
+		prebidWithAdunitCodeJson = json.RawMessage(`{"prebid":{"adunitcode":"adunitcode"}}`)
 	)
 
 	testCases := []struct {
@@ -220,6 +222,13 @@ func TestRebuildImp(t *testing.T) {
 			expectedRequest:   openrtb2.BidRequest{Imp: []openrtb2.Imp{{ID: "2", Ext: prebidJson}}},
 			expectedAccessed:  true,
 		},
+		{
+			description:       "One - Accessed - Dirty - AdUnitCode",
+			request:           openrtb2.BidRequest{Imp: []openrtb2.Imp{{ID: "1"}}},
+			requestImpWrapper: []*ImpWrapper{{Imp: &openrtb2.Imp{ID: "1"}, impExt: &ImpExt{prebid: prebidWithAdunitCode, prebidDirty: true}}},
+			expectedRequest:   openrtb2.BidRequest{Imp: []openrtb2.Imp{{ID: "1", Ext: prebidWithAdunitCodeJson}}},
+			expectedAccessed:  true,
+		},
 		{
 			description:       "One - Accessed - Error",
 			request:           openrtb2.BidRequest{Imp: []openrtb2.Imp{{ID: "1"}}},