Hi, this is what I get with the current CVS (viz later). I know that I don't have libpng, libjpeg etc installed (by mistake, I was compiling on machine without them), but I mean the 'usability ... yes ; presence ... no' problem. Is this an autoconf bug, or is configure.in written badly ? The system is: Debian unstable kernel 2.4.19 (self compiled) autoconf 2.57 automake 1.6.3 gcc/cpp 3.2.2 The results follow. Jan cvs co dillo && cd dillo ./autogen.sh ./configure --prefix=$HOME checking for a BSD-compatible install... /usr/bin/install -c checking whether build environment is sane... yes checking for gawk... gawk checking whether make sets $(MAKE)... yes checking for gcc... gcc checking for C compiler default output... a.out checking whether the C compiler works... yes checking whether we are cross compiling... no checking for suffix of executables... checking for suffix of object files... o checking whether we are using the GNU C compiler... yes checking whether gcc accepts -g... yes checking for gcc option to accept ANSI C... none needed checking for style of include used by make... GNU checking dependency style of gcc... gcc3 checking for gcc option to accept ANSI C... none needed checking for ranlib... ranlib checking for gtk-config... /usr/bin/gtk-config checking for GTK - version >= 1.2.0... yes checking for jpeg_destroy_decompress in -ljpeg... no configure: WARNING: *** JPEG support will not be included *** checking for pthread_create in -lpthread... yes checking for zlibVersion in -lz... no checking for png_check_sig in -lpng... no checking for ANSI C header files... no checking fcntl.h usability... yes checking fcntl.h presence... no configure: WARNING: fcntl.h: accepted by the compiler, rejected by the preprocessor! configure: WARNING: fcntl.h: proceeding with the preprocessor's result configure: WARNING: ## ------------------------------------ ## configure: WARNING: ## Report this to bug-autoconf@gnu.org. ## configure: WARNING: ## ------------------------------------ ## checking for fcntl.h... no checking unistd.h usability... yes checking unistd.h presence... no configure: WARNING: unistd.h: accepted by the compiler, rejected by the preprocessor! configure: WARNING: unistd.h: proceeding with the preprocessor's result configure: WARNING: ## ------------------------------------ ## configure: WARNING: ## Report this to bug-autoconf@gnu.org. ## configure: WARNING: ## ------------------------------------ ## checking for unistd.h... no checking sys/uio.h usability... yes checking sys/uio.h presence... no configure: WARNING: sys/uio.h: accepted by the compiler, rejected by the preprocessor! configure: WARNING: sys/uio.h: proceeding with the preprocessor's result configure: WARNING: ## ------------------------------------ ## configure: WARNING: ## Report this to bug-autoconf@gnu.org. ## configure: WARNING: ## ------------------------------------ ## checking for sys/uio.h... no checking for socket... yes configure: creating ./config.status config.status: creating Makefile config.status: creating doc/Makefile config.status: creating src/Makefile config.status: creating src/IO/Makefile config.status: creating config.h config.status: executing depfiles commands