diff --git a/test/dbus-sdr/sensorcommands_unittest.cpp b/test/dbus-sdr/sensorcommands_unittest.cpp
index 83918c5..bcd2f44 100644
--- a/test/dbus-sdr/sensorcommands_unittest.cpp
+++ b/test/dbus-sdr/sensorcommands_unittest.cpp
@@ -39,6 +39,7 @@
             if (val & 0x80)
                 val++;
             /* Deliberately fall through to case 2. */
+            [[fallthrough]];
         case 2:
             result =
                 (double)(((m * (int8_t)val) + (b * pow(10, k1))) * pow(10, k2));