diff --git a/ChangeLog b/ChangeLog
index bad773fa3..c7f96631e 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -10,6 +10,8 @@
 	that would just crash.
 	In GSRegisterCurrentThread(), add code to handle the case where the
 	NSThread class has not been initialised.
+	* Source/NSObject.m: NSAllocateObject() raise exception if passed
+	something other than a class to allocate an instance of.
 
 2002-05-02  Richard Frith-Macdonald <rfm@gnu.org>
 
diff --git a/Source/NSObject.m b/Source/NSObject.m
index a57e20af1..9fc85c9bc 100644
--- a/Source/NSObject.m
+++ b/Source/NSObject.m
@@ -437,10 +437,11 @@ GSFinalize(void* object, void* data)
 inline NSObject *
 NSAllocateObject(Class aClass, unsigned extraBytes, NSZone *zone)
 {
-  id	new = nil;
-  int	size = aClass->instance_size + extraBytes;
+  id	new;
+  int	size;
 
   NSCAssert((CLS_ISCLASS(aClass)), @"Bad class for new object");
+  size = aClass->instance_size + extraBytes;
   if (zone == GSAtomicMallocZone())
     {
       new = NSZoneMalloc(zone, size);
@@ -522,14 +523,16 @@ NSAllocateObject (Class aClass, unsigned extraBytes, NSZone *zone)
 #ifndef	NDEBUG
   extern void GSDebugAllocationAdd(Class c, id o);
 #endif
-  id new = nil;
-  int size = aClass->instance_size + extraBytes + sizeof(struct obj_layout);
-  if (CLS_ISCLASS (aClass))
+  id	new;
+  int	size;
+
+  NSCAssert((CLS_ISCLASS(aClass)), @"Bad class for new object");
+  size = aClass->instance_size + extraBytes + sizeof(struct obj_layout);
+  if (zone == 0)
     {
-      if (zone == 0)
-	zone = NSDefaultMallocZone();
-      new = NSZoneMalloc(zone, size);
+      zone = NSDefaultMallocZone();
     }
+  new = NSZoneMalloc(zone, size);
   if (new != nil)
     {
       memset (new, 0, size);
@@ -589,10 +592,12 @@ GSObjCZone(NSObject *object)
 inline NSObject *
 NSAllocateObject (Class aClass, unsigned extraBytes, NSZone *zone)
 {
-  id new = nil;
-  int size = aClass->instance_size + extraBytes;
-  if (CLS_ISCLASS (aClass))
-    new = NSZoneMalloc (zone, size);
+  id	new;
+  int	size;
+
+  NSCAssert((CLS_ISCLASS(aClass)), @"Bad class for new object");
+  size = aClass->instance_size + extraBytes;
+  new = NSZoneMalloc (zone, size);
   if (new != nil)
     {
       memset (new, 0, size);