Index: configure.ac
==================================================================
--- configure.ac
+++ configure.ac
@@ -73,11 +73,12 @@
 	AC_MSG_RESULT(yes)
 	], [
 	AC_MSG_RESULT(no)
 	OBJCFLAGS="$old_OBJCFLAGS"
 	])
-AC_CHECK_FUNC(_Block_copy,, AC_SUBST(OFBLOCK_M, "OFBlock.m"))
+AC_CHECK_FUNC(_Block_copy,,
+	AC_DEFINE(HAVE_BLOCK_COPY, 1, [Whether we have _Block_copy]))
 
 AC_CHECK_HEADERS([objfw-rt.h objc/objc.h])
 
 test x"$ac_cv_header_objfw_rt_h" = x"yes" && objc_runtime="ObjFW-RT"
 
@@ -151,10 +152,11 @@
 
 case "$host_os" in
 	darwin*)
 		AC_SUBST(REEXPORT_LIBOBJC, [-Wl,-reexport-lobjc])
 		AC_SUBST(LDFLAGS_REEXPORT, [-Wl,-reexport-lobjfw])
+		AC_SUBST(MACH_ALIAS_LIST, [-Wl,-alias_list,mach_alias_list])
 		;;
 esac
 
 AC_C_BIGENDIAN([
 	AC_DEFINE(OF_BIG_ENDIAN, 1, [Whether we are big endian])

Index: extra.mk.in
==================================================================
--- extra.mk.in
+++ extra.mk.in
@@ -5,13 +5,13 @@
 OBJFW_LIB_MAJOR_MINOR = ${OBJFW_LIB_MAJOR}.${OBJFW_LIB_MINOR}
 
 ASPRINTF_M = @ASPRINTF_M@
 ATOMIC_H = @ATOMIC_H@
 BIN_PREFIX = @BIN_PREFIX@
+MACH_ALIAS_LIST = @MACH_ALIAS_LIST@
 OBJC_PROPERTIES_M = @OBJC_PROPERTIES_M@
 OBJC_SYNC_M = @OBJC_SYNC_M@
-OFBLOCK_M = @OFBLOCK_M@
 OFPLUGIN_M = @OFPLUGIN_M@
 OFPLUGINTESTS_M = @OFPLUGINTESTS_M@
 OFTHREAD_M = @OFTHREAD_M@
 OFTHREADTESTS_M = @OFTHREADTESTS_M@
 PROPERTIESTESTS_M = @PROPERTIESTESTS_M@

Index: src/Makefile
==================================================================
--- src/Makefile
+++ src/Makefile
@@ -6,10 +6,11 @@
 STATIC_LIB = ${OBJFW_STATIC_LIB}
 
 SRCS = OFApplication.m		\
        OFArray.m		\
        OFAutoreleasePool.m	\
+       OFBlock.m		\
        OFConstantString.m	\
        OFDataArray.m		\
        OFDictionary.m		\
        OFExceptions.m		\
        OFFile.m			\
@@ -40,26 +41,24 @@
        OFXMLElementBuilder.m	\
        OFXMLParser.m		\
        unicode.m
 
 INCLUDES := ${SRCS:.m=.h}	\
-	    OFBlock.h		\
 	    OFCollection.h	\
 	    ObjFW.h		\
 	    asprintf.h		\
 	    ${ATOMIC_H}		\
 	    macros.h		\
 	    objfw-defs.h	\
 	    ${THREADING_H}
 
-SRCS += ${OFBLOCK_M}		\
-	${ASPRINTF_M} 		\
+SRCS += ${ASPRINTF_M} 		\
 	iso_8859_15.m		\
 	windows_1252.m		\
 	${OBJC_PROPERTIES_M}	\
 	${OBJC_SYNC_M}
 
 include ../buildsys.mk
 
 CPPFLAGS += -I..
 LD = ${OBJC}
-LDFLAGS += ${REEXPORT_LIBOBJC}
+LDFLAGS += ${REEXPORT_LIBOBJC} ${MACH_ALIAS_LIST}

Index: src/OFBlock.m
==================================================================
--- src/OFBlock.m
+++ src/OFBlock.m
@@ -10,15 +10,15 @@
  */
 
 #include "config.h"
 
 #include <stdint.h>
-#include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
 
 #import "OFBlock.h"
+#import "OFExceptions.h"
 #import "atomic.h"
 
 /// \cond internal
 @protocol RetainRelease
 - retain;
@@ -105,26 +105,32 @@
 {
 	__objc_exec_class(&module);
 }
 /* End of ObjC module */
 #else
-void *_NSConcreteStackBlock;
-void *_NSConcreteGlobalBlock;
-void *_NSConcreteMallocBlock;
+extern void *_NSConcreteStackBlock;
+extern void *_NSConcreteGlobalBlock;
+extern void *_NSConcreteMallocBlock;
 #endif
 
+#ifndef HAVE_BLOCK_COPY
+static struct {
+	Class isa;
+} alloc_failed_exception;
+
 void*
 _Block_copy(const void *block_)
 {
 	of_block_literal_t *block = (of_block_literal_t*)block_;
 
 	if (block->isa == (Class)&_NSConcreteStackBlock) {
 		of_block_literal_t *copy;
 
 		if ((copy = malloc(block->descriptor->size)) == NULL) {
-			fputs("Not enough memory to copy block!\n", stderr);
-			exit(1);
+			alloc_failed_exception.isa =
+			    [OFAllocFailedException class];
+			@throw (OFAllocFailedException*)&alloc_failed_exception;
 		}
 		memcpy(copy, block, block->descriptor->size);
 
 		copy->isa = (Class)&_NSConcreteMallocBlock;
 		copy->reserved++;
@@ -174,13 +180,14 @@
 		of_block_byref_t *src = (of_block_byref_t*)src_;
 		of_block_byref_t **dst = (of_block_byref_t**)dst_;
 
 		if ((src->flags & ~OF_BLOCK_HAS_COPY_DISPOSE) == 0) {
 			if ((*dst = malloc(src->size)) == NULL) {
-				fputs("Not enough memory for block "
-				    "variables!\n", stderr);
-				exit(1);
+				alloc_failed_exception.isa =
+				    [OFAllocFailedException class];
+				@throw (OFAllocFailedException*)
+				    &alloc_failed_exception;
 			}
 
 			if (src->forwarding == src)
 				src->forwarding = *dst;
 
@@ -219,13 +226,18 @@
 			free(obj);
 		}
 		break;
 	}
 }
+#endif
 
 /// \cond internal
 @implementation OFBlock
++ (void)initialize
+{
+}
+
 + (Class)class
 {
 	return self;
 }
 
@@ -237,6 +249,17 @@
 - (void)release
 {
 	Block_release(self);
 }
 @end
+
+#if !defined(OF_GNU_RUNTIME) && !defined(OF_OBJFW_RUNTIME)
+@implementation OFStackBlock
+@end
+
+@implementation OFGlobalBlock
+@end
+
+@implementation OFMallocBlock
+@end
+#endif
 /// \endcond

ADDED   src/mach_alias_list
Index: src/mach_alias_list
==================================================================
--- src/mach_alias_list
+++ src/mach_alias_list
@@ -0,0 +1,4 @@
+# List of aliases for Mach-O
+_OBJC_CLASS_$_OFStackBlock __NSConcreteStackBlock
+_OBJC_CLASS_$_OFGlobalBlock __NSConcreteGlobalBlock
+_OBJC_CLASS_$_OFMallocBlock __NSConcreteMallocBlock