diff --git a/GNUmakefile b/GNUmakefile
index 1fa631b..b54575e 100644
--- a/GNUmakefile
+++ b/GNUmakefile
@@ -31,6 +31,25 @@ libobjc_C_FILES = \
 	selector.c\
 	sendmsg.c\
 	thr.c
+libobjc_HEADER_FILES_DIR = objc
+libobjc_HEADER_FILES_INSTALL_DIR = objc
+libobjc_HEADER_FILES = \
+	Availability.h\
+	NXConstStr.h\
+	Object.h\
+	Protocol.h\
+	blocks_runtime.h\
+	encoding.h\
+	hash.h\
+	objc-api.h\
+	objc-decls.h\
+	objc-list.h\
+	objc.h\
+	runtime-legacy.h\
+	runtime.h\
+	sarray.h\
+	thr.h\
+	typedstream.h
 
 # Deprecated functions are only deprecated for external use, not for us because
 # we are special, precious, little flowers.
diff --git a/blocks_runtime.m b/blocks_runtime.m
index 6c61606..45c0e27 100644
--- a/blocks_runtime.m
+++ b/blocks_runtime.m
@@ -198,7 +198,6 @@ struct StackBlockClass {
 
 
 // Copy a block to the heap if it's still on the stack or increments its retain count.
-// The block is considered on the stack if self->descriptor->reserved == 0.
 void *_Block_copy(void *src)
 {
     struct StackBlockClass *self = src;
diff --git a/objc/runtime.h b/objc/runtime.h
index 77d0583..a3e0c24 100644
--- a/objc/runtime.h
+++ b/objc/runtime.h
@@ -4,6 +4,7 @@
 // If __LEGACY_GNU_MODE__ is defined then we include the old GNU runtime header
 // instead of this one
 #ifndef __OBJC_LEGACY_GNU_MODE__
+#define __GNUSTEP_RUNTIME__
 
 #include <stdint.h>
 #include <stddef.h>
@@ -255,6 +256,10 @@ objc_property_t protocol_getProperty(Protocol *p, const char *name,
 
 BOOL protocol_isEqual(Protocol *p, Protocol *other);
 
+#else
+#include "runtime-legacy.h"
+#endif // __LEGACY_GNU_MODE__
+
 /**
  * The objc_slot structure is used to permit safe IMP caching.  It is returned
  * by the new lookup APIs.  When you cache an IMP, you should store a copy of
@@ -298,7 +303,8 @@ struct objc_slot
  * New ABI lookup function.  Receiver may be modified during lookup or proxy
  * forwarding and the sender may affect how lookup occurs.
  */
-struct objc_slot *objc_msg_lookup_sender(id *receiver, SEL selector, id sender) OBJC_NONPORTABLE;
+struct objc_slot *objc_msg_lookup_sender(id *receiver, SEL selector, id sender)
+	OBJC_NONPORTABLE;
 /**
  * Hook provided to allow libraries to support fast proxies.
  */
@@ -322,8 +328,4 @@ static const id self = nil;
 
 #define objc_msgSendSuper(super, op, ...) objc_msg_lookup_super(super, op)(super->receiver, op, ## __VA_ARGS__)
 
-#else
-#include "runtime-legacy.h"
-#endif // __LEGACY_GNU_MODE__
-
 #endif // __LIBOBJC_RUNTIME_H_INCLUDED__
diff --git a/sendmsg.c b/sendmsg.c
index 161979f..82ef435 100644
--- a/sendmsg.c
+++ b/sendmsg.c
@@ -208,6 +208,7 @@ __objc_responds_to (id object, SEL sel)
   return (res != 0);
 }
 
+extern id (*objc_proxy_lookup)(id receiver, SEL op);
 /* This is the lookup function.  All entries in the table are either a 
    valid method *or* zero.  If zero then either the dispatch table
    needs to be installed or it doesn't exist and forwarding is attempted. */
@@ -243,6 +244,16 @@ objc_msg_lookup (id receiver, SEL op)
                                         (sidx)op->sel_id);
               if (result == 0)
                 {
+                  /* Try again after giving the code a chance to install new
+                   * methods.  This lookup mechanism doesn't support forwarding
+                   * to other objects, so only call the lookup recursively if
+                   * the receiver is not changed.
+                   */
+                  id newReceiver = objc_proxy_lookup (receiver, op);
+                  if (newReceiver == receiver)
+                    {
+                      return objc_msg_lookup(receiver, op);
+                    }
                   /* If the method still just doesn't exist for the
                      class, attempt to forward the method. */
                   result = __objc_get_forward_imp (receiver, op);