diff --git a/tcsh-6.20.00-008-guard-ascii-only-reversion.patch b/tcsh-6.20.00-008-guard-ascii-only-reversion.patch
new file mode 100644
index 0000000..6d1cecd
--- /dev/null
+++ b/tcsh-6.20.00-008-guard-ascii-only-reversion.patch
@@ -0,0 +1,43 @@
+From 8e6dfd53321a0b0047f7d75db21a946c166c600b Mon Sep 17 00:00:00 2001
+From: Christos Zoulas <christos@zoulas.com>
+Date: Fri, 17 Feb 2017 11:17:27 -0500
+Subject: [PATCH] Unfortunately the AsciiOnly reversion causes a SEGV because
+ *ch is used to index in the command array, and now contains INVALID_BYTE. env
+ -i ./tcsh <meta>b
+
+---
+ ed.inputl.c | 18 +++++++++++-------
+ 1 file changed, 11 insertions(+), 7 deletions(-)
+
+diff --git a/ed.inputl.c b/ed.inputl.c
+index f543a6f..1a0d356 100644
+--- a/ed.inputl.c
++++ b/ed.inputl.c
+@@ -796,13 +796,17 @@ GetNextChar(Char *cp)
+ 		return -1;
+ 	    }
+ 	}
+-	cbp++;
+-	if (normal_mbtowc(cp, cbuf, cbp) == -1) {
+-	    reset_mbtowc();
+-	    if (cbp < MB_CUR_MAX)
+-		continue; /* Maybe a partial character */
+-	    /* And drop the following bytes, if any */
+-	    *cp = (unsigned char)*cbuf | INVALID_BYTE;
++	if (AsciiOnly) {
++	    *cp = (unsigned char)*cbuf;
++	} else {
++	    cbp++;
++	    if (normal_mbtowc(cp, cbuf, cbp) == -1) {
++		reset_mbtowc();
++		if (cbp < MB_CUR_MAX)
++		    continue; /* Maybe a partial character */
++		/* And drop the following bytes, if any */
++		*cp = (unsigned char)*cbuf | INVALID_BYTE;
++	    }
+ 	}
+ 	break;
+     }
+-- 
+2.9.3
+
diff --git a/tcsh.spec b/tcsh.spec
index f2df5d4..6833ea5 100644
--- a/tcsh.spec
+++ b/tcsh.spec
@@ -49,6 +49,7 @@ Patch004: tcsh-6.20.00-004-do-not-use-old-pointer-tricks.patch
 Patch005: tcsh-6.20.00-005-reset-fixes-numbering.patch
 Patch006: tcsh-6.20.00-006-cleanup-in-readme-files.patch
 Patch007: tcsh-6.20.00-007-look-for-tgetent-in-libtinfo.patch
+Patch008: tcsh-6.20.00-008-guard-ascii-only-reversion.patch
 
 
 # Downstream patches -- these should be always included when doing rebase:
@@ -181,6 +182,7 @@ fi
     tcsh-6.20.00-005-reset-fixes-numbering.patch
     tcsh-6.20.00-006-cleanup-in-readme-files.patch
     tcsh-6.20.00-007-look-for-tgetent-in-libtinfo.patch
+    tcsh-6.20.00-008-guard-ascii-only-reversion.patch
 
 * Sat Feb 11 2017 Fedora Release Engineering <releng@fedoraproject.org> - 6.20.00-4
 - Rebuilt for https://fedoraproject.org/wiki/Fedora_26_Mass_Rebuild