Index: usr.bin/ar/ar.1
===================================================================
--- usr.bin/ar/ar.1
+++ usr.bin/ar/ar.1
@@ -205,7 +205,12 @@
 .Fl r
 or
 .Fl q
-option, insert 0's instead of the real mtime, uid and gid values
+option,
+with the
+.Fl s
+option without other options, or when invoked as
+.Nm ranlib ,
+insert 0's instead of the real mtime, uid and gid values
 and 0644 instead of file mode from the members named by arguments
 .Ar .
 This ensures that checksums on the resulting archives are reproducible
Index: usr.bin/ar/ar.c
===================================================================
--- usr.bin/ar/ar.c
+++ usr.bin/ar/ar.c
@@ -283,7 +283,8 @@
 	}
 
 	/* Set determinstic mode for -D, and by default without -U. */
-	if (Dflag || (Uflag == 0 && (bsdar->mode == 'q' || bsdar->mode == 'r')))
+	if (Dflag || (Uflag == 0 && (bsdar->mode == 'q' || bsdar->mode == 'r' ||
+	    (bsdar->mode == '\0' && bsdar->options & AR_S))))
 		bsdar->options |= AR_D;
 
 	if (bsdar->options & AR_A)