diff --git a/src/c/threads.d b/src/c/threads.d
index 11f4bbfa2..4d43f1bb0 100644
--- a/src/c/threads.d
+++ b/src/c/threads.d
@@ -466,12 +466,12 @@ mp_get_sigmask(void)
 }
 
 static cl_object
-mp_set_sigmask(cl_object vector)
+mp_set_sigmask(cl_object data)
 {
         sigset_t *mask_ptr = (sigset_t*)data->vector.self.b8;
-        if (pthread_sigmask(SIG_SETMASK, &mask_ptr, NULL))
+        if (pthread_sigmask(SIG_SETMASK, mask_ptr, NULL))
                 FElibc_error("MP:SET-SIGMASK failed in a call to pthread_sigmask", 0);
-        @(return vector)
+        @(return data)
 }
 #endif