diff --git a/endpoints/openrtb2/auction.go b/endpoints/openrtb2/auction.go
index 29f9e98ee5e..fd1803597c3 100644
--- a/endpoints/openrtb2/auction.go
+++ b/endpoints/openrtb2/auction.go
@@ -256,6 +256,11 @@ func (deps *endpointDeps) validateRequest(req *openrtb.BidRequest) []error {
 		return []error{errors.New("request.imp must contain at least one element.")}
 	}
 
+	if len(req.Cur) > 1 {
+		req.Cur = req.Cur[0:1]
+		errL = append(errL, &errortypes.Warning{Message: fmt.Sprintf("A prebid request can only process one currency. Taking the first currency in the list, %s, as the active currency", req.Cur[0])})
+	}
+
 	var aliases map[string]string
 	if bidExt, err := deps.parseBidExt(req.Ext); err != nil {
 		return []error{err}
@@ -1172,7 +1177,7 @@ func writeError(errs []error, w http.ResponseWriter, labels *pbsmetrics.Labels)
 func fatalError(errL []error) bool {
 	for _, err := range errL {
 		errCode := errortypes.DecodeError(err)
-		if errCode != errortypes.BidderTemporarilyDisabledCode || errCode == errortypes.BlacklistedAppCode || errCode == errortypes.BlacklistedAcctCode {
+		if errCode != errortypes.BidderTemporarilyDisabledCode && errCode != errortypes.WarningCode {
 			return true
 		}
 	}
diff --git a/endpoints/openrtb2/auction_test.go b/endpoints/openrtb2/auction_test.go
index de330ed617e..4818c556661 100644
--- a/endpoints/openrtb2/auction_test.go
+++ b/endpoints/openrtb2/auction_test.go
@@ -865,6 +865,54 @@ func validRequest(t *testing.T, filename string) string {
 	return string(requestData)
 }
 
+func TestCurrencyTrunc(t *testing.T) {
+	deps := &endpointDeps{
+		&nobidExchange{},
+		newParamsValidator(t),
+		&mockStoredReqFetcher{},
+		empty_fetcher.EmptyFetcher{},
+		empty_fetcher.EmptyFetcher{},
+		&config.Configuration{},
+		pbsmetrics.NewMetrics(metrics.NewRegistry(), openrtb_ext.BidderList(), config.DisabledMetrics{}),
+		analyticsConf.NewPBSAnalytics(&config.Analytics{}),
+		map[string]string{},
+		false,
+		[]byte{},
+		openrtb_ext.BidderMap,
+	}
+
+	ui := uint64(1)
+	req := openrtb.BidRequest{
+		ID: "someID",
+		Imp: []openrtb.Imp{
+			{
+				ID: "imp-ID",
+				Banner: &openrtb.Banner{
+					W: &ui,
+					H: &ui,
+				},
+				Ext: json.RawMessage("{\"appnexus\": {\"placementId\": 5667}}"),
+			},
+		},
+		Site: &openrtb.Site{
+			ID: "myID",
+		},
+		Cur: []string{"USD", "EUR"},
+	}
+
+	errL := deps.validateRequest(&req)
+	for _, err := range errL {
+		if err.Error() != "A prebid request can only process one currency. Taking the first currency in the list, USD, as the active currency" {
+			t.Errorf(err.Error())
+		} else {
+			if errortypes.DecodeError(err) != errortypes.WarningCode {
+				t.Errorf("The expected warning has the wrong error type/code")
+			}
+		}
+	}
+	assert.Len(t, req.Cur, 1)
+}
+
 // nobidExchange is a well-behaved exchange which always bids "no bid".
 type nobidExchange struct {
 	gotRequest *openrtb.BidRequest
diff --git a/errortypes/errortypes.go b/errortypes/errortypes.go
index 731bf59df07..4bcea24f737 100644
--- a/errortypes/errortypes.go
+++ b/errortypes/errortypes.go
@@ -12,6 +12,7 @@ const (
 	BidderTemporarilyDisabledCode
 	BlacklistedAcctCode
 	AcctRequiredCode
+	WarningCode
 )
 
 // We should use this code for any Error interface that is not in this package
@@ -155,6 +156,20 @@ func (err *BidderTemporarilyDisabled) Code() int {
 	return BidderTemporarilyDisabledCode
 }
 
+// Warning is a generic warning type, not a serious error
+type Warning struct {
+	Message string
+}
+
+func (err *Warning) Error() string {
+	return err.Message
+}
+
+// Code returns the error code
+func (err *Warning) Code() int {
+	return WarningCode
+}
+
 // DecodeError provides the error code for an error, as defined above
 func DecodeError(err error) int {
 	if ce, ok := err.(Coder); ok {