diff --git a/ChangeLog b/ChangeLog
index 6541bdb0f..09df693ba 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,9 @@
+2010-03-12 Richard Frith-Macdonald <rfm@gnu.org>
+
+	* Source/NSKeyedArchiver.m:
+	Create _+clsMap lazily so it's there for subclasses even if the
+	initialiser was not called.
+
 2010-03-11 12:14-EST Gregory John Casamento <greg.casamento@gmail.com>
 
 	* Source/GNUmakefile: Remove reference to synchonization.m.
diff --git a/Source/NSKeyedUnarchiver.m b/Source/NSKeyedUnarchiver.m
index c12eeab59..1f098b16c 100644
--- a/Source/NSKeyedUnarchiver.m
+++ b/Source/NSKeyedUnarchiver.m
@@ -345,7 +345,7 @@ static NSMapTable	*globalClassMap = 0;
 
 - (Class) classForClassName: (NSString*)aString
 {
-  return (Class)NSMapGet(_clsMap, (void*)aString);
+  return _clsMap == 0 ? Nil : (Class)NSMapGet(_clsMap, (void*)aString);
 }
 
 - (BOOL) containsValueForKey: (NSString*)aKey
@@ -806,8 +806,6 @@ static NSMapTable	*globalClassMap = 0;
 	  _objects = [_archive objectForKey: @"$objects"];
 	  _keyMap = [_archive objectForKey: @"$top"];
 
-	  _clsMap = NSCreateMapTable(NSObjectMapKeyCallBacks,
-	    NSNonOwnedPointerMapValueCallBacks, 0);
 #if	GS_WITH_GC
 	  _objMap = NSAllocateCollectable(sizeof(GSIArray_t), NSScannedOption);
 #else
@@ -831,10 +829,18 @@ static NSMapTable	*globalClassMap = 0;
 {
   if (aString == nil)
     {
-      NSMapRemove(_clsMap, (void*)aString);
+      if (_clsMap != 0)
+	{
+          NSMapRemove(_clsMap, (void*)aString);
+	}
     }
   else
     {
+      if (_clsMap == 0)
+	{
+	  _clsMap = NSCreateMapTable(NSObjectMapKeyCallBacks,
+	    NSNonOwnedPointerMapValueCallBacks, 0);
+	}
       NSMapInsert(_clsMap, (void*)aString, (void*)aClass);
     }
 }