diff --git a/include/search.h b/include/search.h
index 75f59bf2d1a7..f0ef44357533 100644
--- a/include/search.h
+++ b/include/search.h
@@ -44,7 +44,8 @@ __BEGIN_DECLS
 int	 hcreate(size_t);
 void	 hdestroy(void);
 ENTRY	*hsearch(ENTRY, ACTION);
-void	*tdelete(const void *, void **, int (*)(const void *, const void *));
+void	*tdelete(const void *__restrict, void **__restrict,
+	    int (*)(const void *, const void *));
 void	*tfind(const void *, void **, int (*)(const void *, const void *));
 void	*tsearch(const void *, void **, int (*)(const void *, const void *));
 void      twalk(const void *, void (*)(const void *, VISIT, int));
diff --git a/lib/libc/stdlib/tdelete.c b/lib/libc/stdlib/tdelete.c
index 32dc298c6ea6..5729bd5aa33e 100644
--- a/lib/libc/stdlib/tdelete.c
+++ b/lib/libc/stdlib/tdelete.c
@@ -25,16 +25,20 @@ __FBSDID("$FreeBSD$");
 #include <stdlib.h>
 
 
-/* delete node with given key */
+/*
+ * delete node with given key
+ *
+ * vkey:   key to be deleted
+ * vrootp: address of the root of the tree
+ * compar: function to carry out node comparisons
+ */
 void *
-tdelete(vkey, vrootp, compar)
-	const void *vkey;	/* key to be deleted */
-	void      **vrootp;	/* address of the root of tree */
-	int       (*compar)(const void *, const void *);
+tdelete(const void *__restrict vkey, void **__restrict vrootp,
+    int (*compar)(const void *, const void *))
 {
 	node_t **rootp = (node_t **)vrootp;
 	node_t *p, *q, *r;
-	int  cmp;
+	int cmp;
 
 	if (rootp == NULL || (p = *rootp) == NULL)
 		return NULL;
diff --git a/lib/libc/stdlib/tsearch.3 b/lib/libc/stdlib/tsearch.3
index 87a2571bc15f..06ff72098a98 100644
--- a/lib/libc/stdlib/tsearch.3
+++ b/lib/libc/stdlib/tsearch.3
@@ -36,7 +36,7 @@
 .Sh SYNOPSIS
 .In search.h
 .Ft void *
-.Fn tdelete "const void *key" "void **rootp" "int (*compar) (const void *, const void *)"
+.Fn tdelete "const void *restrict key" "void **restrict rootp" "int (*compar) (const void *, const void *)"
 .Ft void *
 .Fn tfind "const void *key" "void **rootp" "int (*compar) (const void *, const void *)"
 .Ft void *