Hi, libshims also needs the blocks headers in order to compile. ciao, Mario Index: src/Makefile.am =================================================================== --- src/Makefile.am (Revision 171) +++ src/Makefile.am (Arbeitskopie) @@ -26,6 +26,7 @@ @APPLE_LIBC_SOURCE_PATH@ @APPLE_XNU_SOURCE_PATH@ libdispatch_la_CFLAGS+=$(MARCH_FLAGS) $(CBLOCKS_FLAGS) $(KQUEUE_CFLAGS) +libshims_la_CFLAGS=$(CBLOCKS_FLAGS) if USE_LEGACY_API libdispatch_la_SOURCES+= \