diff --git a/src/core/unit.c b/src/core/unit.c
index e865c393a3b..66ac9c91ec0 100644
--- a/src/core/unit.c
+++ b/src/core/unit.c
@@ -5079,10 +5079,7 @@ bool unit_type_supported(UnitType t) {
         static int8_t cache[_UNIT_TYPE_MAX] = {}; /* -1: disabled, 1: enabled: 0: don't know */
         int r;
 
-        if (_unlikely_(t < 0))
-                return false;
-        if (_unlikely_(t >= _UNIT_TYPE_MAX))
-                return false;
+        assert(t >= 0 && t < _UNIT_TYPE_MAX);
 
         if (cache[t] == 0) {
                 char *e;