diff --git a/ChangeLog b/ChangeLog
index d906e6fc4..5f3543245 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+2001-02-08  Richard Frith-Macdonald <rfm@gnu.org>
+
+	* Source/GSString.m: permit nil string when replacing characters
+	in range.  Treat as an empty string rather than raising exception.
+
 2001-02-07  Jonathan Gapen  <jagapen@home.com>
 
 	* Source/NSFileManager.m: Make disk space report work on FreeBSD.
diff --git a/Source/GSString.m b/Source/GSString.m
index eb757d02e..3ae690d0c 100644
--- a/Source/GSString.m
+++ b/Source/GSString.m
@@ -2581,13 +2581,19 @@ transmute(ivars self, NSString *aString)
 
   GS_RANGE_CHECK(aRange, _count);
   if (aString == nil)
-    [NSException raise: NSInvalidArgumentException
-		format: @"replace characters with nil string"];
-  if (GSObjCIsInstance(aString) == NO)
-    [NSException raise: NSInvalidArgumentException
-		format: @"replace characters with non-string"];
+    {
+      length = 0;
+    }
+  else if (GSObjCIsInstance(aString) == NO)
+    {
+      [NSException raise: NSInvalidArgumentException
+		  format: @"replace characters with non-string"];
+    }
+  else
+    {
+      length = (aString == nil) ? 0 : [aString length];
+    }
 
-  length = (aString == nil) ? 0 : [aString length];
   offset = length - aRange.length;
 
   if (offset < 0)