diff --git a/ChangeLog b/ChangeLog
index d7b57583c..72b6e6265 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,9 @@
+2010-06-07  Richard Frith-Macdonald <rfm@gnu.org>
+
+	* Source/GSFFIInvocation.m: Fix breakage caused by David's changes.
+	* Source/ObjectiveC2/runtime.m: Fix handling of nul arguments in
+	class_sespondsToSelector().
+	
 2010-06-05  Richard Frith-Macdonald <rfm@gnu.org>
 
 	* Tools/Makefile.postamble: Fix breakage of instalation of gdomap
diff --git a/Source/GSFFIInvocation.m b/Source/GSFFIInvocation.m
index 86cbdb2b1..dfcb05106 100644
--- a/Source/GSFFIInvocation.m
+++ b/Source/GSFFIInvocation.m
@@ -22,8 +22,6 @@
    Boston, MA 02111 USA.
    */
 
-#define class_pointer isa
-
 #import "common.h"
 #define	EXPOSE_NSInvocation_IVARS	1
 #import "Foundation/NSException.h"
@@ -147,21 +145,18 @@ static IMP gs_objc_msg_forward2 (id receiver, SEL sel)
   ffi_closure           *cclosure;
   NSMethodSignature     *sig;
   GSCodeBuffer          *memory;
+  Class			c;
 
-  if (class_respondsToSelector(receiver->isa, sel) ||
-     (class_respondsToSelector(receiver->isa, @selector(respondsToSelector:))
-           && [receiver respondsToSelector: sel]))
+  c = object_getClass(receiver);
+  if (class_respondsToSelector(c, sel)
+    || (class_respondsToSelector(c, @selector(respondsToSelector:))
+      && [receiver respondsToSelector: sel]))
     {
       sig = [receiver methodSignatureForSelector: sel];
     }
   else
     {
-      [NSException raise: NSInvalidArgumentException
-		   format: @"GSFFIInvocation: Class '%s'(%s) does not respond"
-		           @" to forwardInvocation: for '%s'",
-		   GSClassNameFromObject(receiver),
-		   GSObjCIsInstance(receiver) ? "instance" : "class",
-		   sel ? sel_getName(sel) : "(null)"];
+      sig = nil;
     }
 
   if (sig == nil)
diff --git a/Source/ObjectiveC2/runtime.c b/Source/ObjectiveC2/runtime.c
index 028737e68..488d69e42 100644
--- a/Source/ObjectiveC2/runtime.c
+++ b/Source/ObjectiveC2/runtime.c
@@ -518,7 +518,9 @@ class_replaceMethod(Class cls, SEL name, IMP imp, const char *types)
 BOOL
 class_respondsToSelector(Class cls, SEL sel)
 {
-  return __objc_responds_to((id) & cls, sel);
+  if (cls != 0 && sel != 0 && __objc_responds_to((id) & cls, sel) != 0)
+    return YES;
+  return NO;
 }
 
 void