diff --git a/src/core/execute.c b/src/core/execute.c
index a9b2b8f299..53356c3c06 100644
--- a/src/core/execute.c
+++ b/src/core/execute.c
@@ -788,6 +788,19 @@ static int get_fixed_supplementary_groups(const ExecContext *c,
         if (!c->supplementary_groups)
                 return 0;
 
+        /*
+         * If SupplementaryGroups= was passed then NGROUPS_MAX has to
+         * be positive, otherwise fail.
+         */
+        errno = 0;
+        ngroups_max = (int) sysconf(_SC_NGROUPS_MAX);
+        if (ngroups_max <= 0) {
+                if (errno > 0)
+                        return -errno;
+                else
+                        return -EOPNOTSUPP; /* For all other values */
+        }
+
         /*
          * If user is given, then lookup GID and supplementary group list.
          * We avoid NSS lookups for gid=0.
@@ -800,8 +813,6 @@ static int get_fixed_supplementary_groups(const ExecContext *c,
                 keep_groups = true;
         }
 
-        assert_se((ngroups_max = (int) sysconf(_SC_NGROUPS_MAX)) > 0);
-
         l_gids = new(gid_t, ngroups_max);
         if (!l_gids)
                 return -ENOMEM;