diff --git a/mbus/mbus-protocol-aux.c b/mbus/mbus-protocol-aux.c
index 52f11e9..57758eb 100755
--- a/mbus/mbus-protocol-aux.c
+++ b/mbus/mbus-protocol-aux.c
@@ -974,7 +974,8 @@ mbus_vif_unit_normalize(int vif, double value, char **unit_out, double *value_ou
         }
     }
 
-    *unit_out = strdup("Unknown (VIF=0x%.2X)");
+    MBUS_ERROR("%s: Unknown VIF 0x%03X\n", __PRETTY_FUNCTION__, newVif);
+    *unit_out = strdup("Unknown (VIF=0x%.02X)");
     *quantity_out = strdup("Unknown");
     exponent = 0.0;
     *value_out = 0.0;