diff --git a/src/driver_ultraheat.cc b/src/driver_ultraheat.cc
index 064ed52..da79a4b 100644
--- a/src/driver_ultraheat.cc
+++ b/src/driver_ultraheat.cc
@@ -62,7 +62,7 @@ namespace
             "The current power consumption.",
             DEFAULT_PRINT_PROPERTIES,
             Quantity::Power,
-            VifScaling::Auto,
+            VifScaling::AutoSigned,
             FieldMatcher::build()
             .set(MeasurementType::Instantaneous)
             .set(VIFRange::PowerW)
@@ -73,7 +73,7 @@ namespace
             "The current heat media volume flow.",
             DEFAULT_PRINT_PROPERTIES,
             Quantity::Flow,
-            VifScaling::Auto,
+            VifScaling::AutoSigned,
             FieldMatcher::build()
             .set(MeasurementType::Instantaneous)
             .set(VIFRange::VolumeFlow)