Index: src/backend/utils/adt/char.c
===================================================================
--- src/backend/utils/adt/char.c	(revision 1156)
+++ src/backend/utils/adt/char.c	(working copy)
@@ -34,6 +34,11 @@
 {
 	char	   *ch = PG_GETARG_CSTRING(0);
 
+	if (ch[0] != '\0' && ch[1] != '\0')
+		ereport(ERROR,
+			(errcode(ERRCODE_STRING_DATA_RIGHT_TRUNCATION),
+			 errmsg("value too long for type \"char\"")));
+
 	PG_RETURN_CHAR(ch[0]);
 }
 
@@ -67,6 +72,11 @@
 {
 	StringInfo	buf = (StringInfo) PG_GETARG_POINTER(0);
 
+	if (buf->len > 1)
+		ereport(ERROR,
+			(errcode(ERRCODE_STRING_DATA_RIGHT_TRUNCATION),
+			 errmsg("value too long for type \"char\"")));
+
 	PG_RETURN_CHAR(pq_getmsgbyte(buf));
 }