diff --git a/src/buffer.c b/src/buffer.c
index 55cef35..c9a91ce 100644
--- a/src/buffer.c
+++ b/src/buffer.c
@@ -1208,11 +1208,11 @@
     {
 # ifdef FEAT_WINDOWS
 	/* jump to first window containing buf if one exists ("useopen") */
-	if (vim_strchr(p_swb, 'o') && buf_jump_open_win(buf))
+	if (vim_strchr(p_swb, 'o') != NULL && buf_jump_open_win(buf))
 	    return OK;
 	/* jump to first window in any tab page containing buf if one exists
 	 * ("usetab") */
-	if (vim_strchr(p_swb, 'a') && buf_jump_open_tab(buf))
+	if (vim_strchr(p_swb, 'a') != NULL && buf_jump_open_tab(buf))
 	    return OK;
 	if (win_split(0, 0) == FAIL)
 # endif
@@ -1842,13 +1842,13 @@
     if (options & GETF_SWITCH)
     {
 	/* use existing open window for buffer if wanted */
-	if (vim_strchr(p_swb, 'o'))     /* useopen */
+	if (vim_strchr(p_swb, 'o') != NULL)	/* useopen */
 	    wp = buf_jump_open_win(buf);
 	/* use existing open window in any tab page for buffer if wanted */
-	if (vim_strchr(p_swb, 'a'))     /* usetab */
+	if (vim_strchr(p_swb, 'a') != NULL)	/* usetab */
 	    wp = buf_jump_open_tab(buf);
 	/* split window if wanted ("split") */
-	if (wp == NULL && vim_strchr(p_swb, 't') && !bufempty())
+	if (wp == NULL && vim_strchr(p_swb, 'l') != NULL && !bufempty())
 	{
 	    if (win_split(0, 0) == FAIL)
 		return FAIL;