diff --git a/src/edit.c b/src/edit.c
index 9435fd6..f89d43e 100644
--- a/src/edit.c
+++ b/src/edit.c
@@ -5318,7 +5318,7 @@
 	    // was typed after a CTRL-V, and pretend 'textwidth'
 	    // wasn't set.  Digits, 'o' and 'x' are special after a
 	    // CTRL-V, don't use it for these.
-	    if (c < 256 && !isalnum(c))
+	    if (c < 256 && !SAFE_isalnum(c))
 		AppendToRedobuff((char_u *)CTRL_V_STR);	// CTRL-V
 	    tw_save = curbuf->b_p_tw;
 	    curbuf->b_p_tw = -1;