diff --git a/pkg/registry/service_registry.go b/pkg/registry/service_registry.go
index 316a60fc9d7..b859c50899f 100644
--- a/pkg/registry/service_registry.go
+++ b/pkg/registry/service_registry.go
@@ -50,7 +50,7 @@ func makeLinkVariables(service api.Service, machine string) []api.EnvVar {
 	} else {
 		port = strconv.Itoa(service.ContainerPort.IntVal)
 	}
-	portPrefix := prefix + "_PORT_" + port + "_TCP"
+	portPrefix := prefix + "_PORT_" + strings.ToUpper(strings.Replace(port,"-","_",-1)) + "_TCP"
 	return []api.EnvVar{
 		{
 			Name:  prefix + "_PORT",
diff --git a/pkg/registry/service_registry_test.go b/pkg/registry/service_registry_test.go
index ae117bdf777..02d5f67d7f3 100644
--- a/pkg/registry/service_registry_test.go
+++ b/pkg/registry/service_registry_test.go
@@ -23,6 +23,7 @@ import (
 	"github.com/GoogleCloudPlatform/kubernetes/pkg/api"
 	"github.com/GoogleCloudPlatform/kubernetes/pkg/apiserver"
 	"github.com/GoogleCloudPlatform/kubernetes/pkg/cloudprovider"
+	"github.com/GoogleCloudPlatform/kubernetes/pkg/util"
 )
 
 func TestServiceRegistry(t *testing.T) {
@@ -216,3 +217,17 @@ func TestServiceRegistryDeleteExternal(t *testing.T) {
 		}
 	}
 }
+
+func TestServiceRegistryMakeLinkVariables(t *testing.T) {
+	service := api.Service {
+		JSONBase:	api.JSONBase{ID: "foo"},
+		Selector:	map[string]string{"bar": "baz"},
+		ContainerPort:	util.IntOrString { Kind: util.IntstrString, StrVal: "a-b-c" },
+	}
+	vars := makeLinkVariables(service, "mars")
+	for _, v := range vars {
+		if !util.IsCIdentifier(v.Name) {
+			t.Errorf("Environment variable name is not valid: %v", v.Name)
+		}
+	}
+}