diff --git a/sys/sys/sdt.h b/sys/sys/sdt.h
index fb5c3d671604..2407ef88ab56 100644
--- a/sys/sys/sdt.h
+++ b/sys/sys/sdt.h
@@ -86,6 +86,8 @@ extern volatile bool sdt_probes_enabled;
 
 #ifndef KDTRACE_HOOKS
 
+#define __sdt_used	__unused
+
 #define SDT_PROVIDER_DEFINE(prov)
 #define SDT_PROVIDER_DECLARE(prov)
 #define SDT_PROBE_DEFINE(prov, mod, func, name)
@@ -141,6 +143,8 @@ extern volatile bool sdt_probes_enabled;
 
 #else
 
+#define __sdt_used
+
 SET_DECLARE(sdt_providers_set, struct sdt_provider);
 SET_DECLARE(sdt_probes_set, struct sdt_probe);
 SET_DECLARE(sdt_argtypes_set, struct sdt_argtype);