diff --git a/include/time.h b/include/time.h
index dd576708f441..e17feb3b2427 100644
--- a/include/time.h
+++ b/include/time.h
@@ -143,7 +143,8 @@ struct tm *localtime_r(const time_t *, struct tm *);
 #endif
 
 #if __XSI_VISIBLE
-char *strptime(const char *, const char *, struct tm *);
+char *strptime(const char *__restrict, const char *__restrict,
+    struct tm *__restrict);
 #endif
 
 #if __BSD_VISIBLE
diff --git a/lib/libc/stdtime/strptime.3 b/lib/libc/stdtime/strptime.3
index e04678dff1e8..36ca7e074ef2 100644
--- a/lib/libc/stdtime/strptime.3
+++ b/lib/libc/stdtime/strptime.3
@@ -36,7 +36,7 @@
 .Sh SYNOPSIS
 .In time.h
 .Ft char *
-.Fn strptime "const char *buf" "const char *format" "struct tm *timeptr"
+.Fn strptime "const char *restrict buf" "const char *restrict format" "struct tm *restrict timeptr"
 .Sh DESCRIPTION
 The
 .Fn strptime
diff --git a/lib/libc/stdtime/strptime.c b/lib/libc/stdtime/strptime.c
index b050f1ae92a6..be844820df31 100644
--- a/lib/libc/stdtime/strptime.c
+++ b/lib/libc/stdtime/strptime.c
@@ -517,7 +517,8 @@ _strptime(const char *buf, const char *fmt, struct tm *tm)
 
 
 char *
-strptime(const char *buf, const char *fmt, struct tm *tm)
+strptime(const char *__restrict buf, const char *__restrict fmt,
+    struct tm *__restrict tm)
 {
 	char *ret;