diff --git a/isearch.c b/isearch.c
index 97f4339..d9532fb 100644
--- a/isearch.c
+++ b/isearch.c
@@ -198,7 +198,8 @@ static int isearch(int f, int n)
 	cmd_reexecute = -1;	/* We're not re-executing (yet?)      */
 	cmd_offset = 0;		/* Start at the beginning of the buff */
 	cmd_buff[0] = '\0';	/* Init the command buffer            */
-	strncpy( pat_save, pat, sizeof pat_save) ;	/* Save the old pattern string        */
+	strncpy( pat_save, pat, sizeof pat_save - 1) ;	/* Save the old pattern string        */
+	pat_save[ sizeof pat_save - 1] = '\0' ;
 	curline = curwp->w_dotp;	/* Save the current line pointer      */
 	curoff = curwp->w_doto;	/* Save the current offset            */
 	init_direction = n;	/* Save the initial search direction  */