diff --git a/api/impl.go b/api/impl.go
index 0d14f05f0..e2157fcf8 100644
--- a/api/impl.go
+++ b/api/impl.go
@@ -11,7 +11,9 @@ func ChargeModeString(mode string) ChargeMode {
 		return ModeMinPV
 	case string(ModePV):
 		return ModePV
-	default:
+	case string(ModeOff):
 		return ModeOff
+	default:
+		return ""
 	}
 }
diff --git a/server/http.go b/server/http.go
index 744f3ffd2..fc5122aac 100644
--- a/server/http.go
+++ b/server/http.go
@@ -177,7 +177,7 @@ func ChargeModeHandler(loadpoint loadpoint) http.HandlerFunc {
 
 		modeS, ok := vars["mode"]
 		mode := api.ChargeModeString(modeS)
-		if string(mode) != modeS || !ok {
+		if mode == "" || string(mode) != modeS || !ok {
 			w.WriteHeader(http.StatusBadRequest)
 			return
 		}