diff --git a/src/eval.c b/src/eval.c
index ef9b6d1..be59f98 100644
--- a/src/eval.c
+++ b/src/eval.c
@@ -18309,8 +18309,8 @@
 # ifdef FEAT_MBYTE
     if (eap->force_enc != 0)
 	len += (unsigned)STRLEN(eap->cmd + eap->force_enc) + 7;
-    if (eap->bad_char_idx != 0)
-	len += (unsigned)STRLEN(eap->cmd + eap->bad_char_idx) + 7;
+    if (eap->bad_char != 0)
+	len += 7 + 4;  /* " ++bad=" + "keep" or "drop" */
 # endif
 
     newval = alloc(len + 1);
@@ -18334,9 +18334,12 @@
     if (eap->force_enc != 0)
 	sprintf((char *)newval + STRLEN(newval), " ++enc=%s",
 					       eap->cmd + eap->force_enc);
-    if (eap->bad_char_idx != 0)
-	sprintf((char *)newval + STRLEN(newval), " ++bad=%s",
-					       eap->cmd + eap->bad_char_idx);
+    if (eap->bad_char == BAD_KEEP)
+	STRCPY(newval + STRLEN(newval), " ++bad=keep");
+    else if (eap->bad_char == BAD_DROP)
+	STRCPY(newval + STRLEN(newval), " ++bad=drop");
+    else if (eap->bad_char != 0)
+	sprintf((char *)newval + STRLEN(newval), " ++bad=%c", eap->bad_char);
 # endif
     vimvars[VV_CMDARG].vv_str = newval;
     return oldval;