diff -r ab36689121ad src/screen.c
--- a/src/screen.c	Wed Dec 17 21:00:49 2014 +0100
+++ b/src/screen.c	Mon Jan 05 13:57:05 2015 -0300
@@ -6059,15 +6059,22 @@
 	/* For a window that's left of another, draw the separator char. */
 	if (col + coloff < Columns)
 	{
-	    int c;
-
-	    c = fillchar_vsep(&hl);
-	    if (ScreenLines[off_to] != c
+	    int c = fillchar_vsep(&hl);
+	    int modified;
+
 # ifdef FEAT_MBYTE
-		    || (enc_utf8 && (int)ScreenLinesUC[off_to]
-						       != (c >= 0x80 ? c : 0))
-# endif
-		    || ScreenAttrs[off_to] != hl)
+	    if (enc_utf8)
+	    {
+		modified = (ScreenLinesUC[off_to] !=
+		       	(u8char_T)(c >= 0x80 ? c : 0));
+	    }
+	    else
+# endif
+	    {
+		modified = ScreenLines[off_to] != c;
+	    }
+
+	    if (modified || ScreenAttrs[off_to] != hl)
 	    {
 		ScreenLines[off_to] = c;
 		ScreenAttrs[off_to] = hl;