diff --git a/build.zig b/build.zig
index a16583e..7c1148b 100644
--- a/build.zig
+++ b/build.zig
@@ -49,17 +49,19 @@ pub fn build(b: *std.Build) void {
 
     const run_unit_tests = b.addRunArtifact(unit_tests);
 
-    if (setcap and sudo == null) {
-        std.log.warn("non-null setcap and no sudo command probably won't work. Add sudo.", .{});
-    }
-
+    // TODO learn `zig build` and complain only during unit tests.
     if (setcap) {
+        if (sudo == null) {
+            std.log.warn("non-null setcap and no sudo command probably won't work. Add sudo.", .{});
+        }
         const set_cap_cmd = b.addSystemCommand(if (sudo) |cmd|
             &.{ cmd, "setcap", "cap_net_admin=+ep" }
         else
             &.{ "setcap", "cap_net_admin=+ep" });
         set_cap_cmd.addArtifactArg(unit_tests);
         run_unit_tests.step.dependOn(&set_cap_cmd.step);
+    } else {
+        std.log.warn("-Dsetcap not set. Unit tests will probably fail.", .{});
     }
 
     // Similar to creating the run step earlier, this exposes a `test` step to