diff --git a/.github/workflows/main.yml b/.github/workflows/main.yml
index 81395019e..29e91c3a5 100644
--- a/.github/workflows/main.yml
+++ b/.github/workflows/main.yml
@@ -53,7 +53,7 @@ jobs:
             echo $PATH
 
       - name: build
-        run: ./build.sh auto allimages
+        run: ./build.sh auto ext allimages
 
       - name: upload
         uses: actions/upload-artifact@v4
diff --git a/Makefile b/Makefile
index f3c483c2f..a8c64fc14 100644
--- a/Makefile
+++ b/Makefile
@@ -1,6 +1,6 @@
 
 ifndef TOPDIR
-$(error TOPDIR is not defined; did you mean to run './build.sh' instead?)
+$(error TOPDIR is not defined; run '. ./env.sh' then './build.sh' to build toolchain)
 endif
 
 include $(TOPDIR)/Make.defs
diff --git a/build.sh b/build.sh
index 09667ab99..4f4bc51ee 100755
--- a/build.sh
+++ b/build.sh
@@ -1,10 +1,20 @@
 #!/usr/bin/env bash
 
-# This build script is called in main.yml by GitHub Continuous Integration
-# Full build (including the cross tool chain)
-
-# Arguments:
-#   - 'auto' : continuous integration context
+# ELKS System Builder
+# This build script is also called in main.yml for GitHub Continuous Integration
+#
+# Usage: ./build.sh [auto [[ext] [[[allimages]]]]]
+#   <no args>:  user build: build cross-compiler, menuconfig kernel and standard apps
+#   auto        github CI build:: just IBM PC, 8018X, NECV25 kernel and standard apps
+#   ext         also build external apps (requires OpenWatcom C installed)
+#   allimages   also build all floppy and HD disk images
+#
+# After building the system once, the following can be used to rebuild the system:
+#   $ make clean
+#   $ make
+#   $ ./buildext.sh all     # optionally build specified external apps (OpenWatcom reqd)
+#   $ ./qemu.sh
+#
 set -e
 
 SCRIPTDIR="$(dirname "$0")"
@@ -63,12 +73,14 @@ if [ "$1" != "auto" ]; then
 echo "Building all..."
 make -j1 all || clean_exit 5
 
-echo "Building external applications..."
-./buildext.sh all || clean_exit 51
+if [ "$2" = "ext" ]; then
+    echo "Building external applications..."
+    ./buildext.sh all || clean_exit 51
+fi
 
 # Possibly build all images
 
-if [ "$2" = "allimages" ]; then
+if [ "$3" = "allimages" ]; then
 	echo "Building FD images..."
 	cd image
 	make -j1 images-minix images-fat || clean_exit 6
diff --git a/elks/tools/mtools/Makefile b/elks/tools/mtools/Makefile
index 64428e4ce..30d5aefd2 100644
--- a/elks/tools/mtools/Makefile
+++ b/elks/tools/mtools/Makefile
@@ -51,6 +51,9 @@ all: mtools-4.0.23/Makefile
 
 mtools-4.0.23/Makefile:
 	cd mtools-4.0.23; ./configure --disable-floppyd; cd ..
+	case `uname -s` in Darwin) \
+	    sed -i.bak 's/^#define HAVE_STAT64 1//' mtools-4.0.23/config.h && \
+	    rm -f mtools-4.0.23/config.h.bak ;; esac
 
 clean:
 	make -C mtools-4.0.23 clean
diff --git a/qemu.sh b/qemu.sh
index 6efd75d2f..a558eec65 100755
--- a/qemu.sh
+++ b/qemu.sh
@@ -130,7 +130,7 @@ ACCEL_V9="-accel tcg,one-insn-per-tb=on"
 ACCEL_HVF="-accel hvf"
 
 ACCEL=$ACCEL_SSTP
-if [[ `$QEMU -version` =~ "version 9" ]]; then
+if [[ `$QEMU -version` =~ "version 9" || `$QEMU -version` =~ "version 10" ]]; then
      ACCEL=$ACCEL_V9
 fi
 if [[ $QEMU =~ "x86_64" && $UNAME =~ "Darwin" && $UNAME =~ "x86_64" ]]; then
diff --git a/tools/Makefile b/tools/Makefile
index 0e1c6cfe7..baec444c6 100644
--- a/tools/Makefile
+++ b/tools/Makefile
@@ -23,7 +23,7 @@ BUILDDIR=$(CROSSDIR)/build
 
 # BINUTILS for IA16
 
-BINUTILS_VER=cc5f1a9d7437051c3aae6ec16fca27c3b2d31f6c
+BINUTILS_VER=69e12ea2c125ff830580abbe4699d35ba002148b
 BINUTILS_DIST=binutils-ia16-$(BINUTILS_VER)
 
 $(DISTDIR)/$(BINUTILS_DIST).tar.gz:
@@ -45,6 +45,13 @@ $(BUILDDIR)/.binutils.src: $(DISTDIR)/$(BINUTILS_DIST).tar.gz
 	cd $(BUILDDIR) && tar -xzf $(DISTDIR)/$(BINUTILS_DIST).tar.gz
 	rm -rf $(BUILDDIR)/binutils-src
 	cd $(BUILDDIR) && mv $(BINUTILS_DIST) binutils-src
+	case `uname -s` in Darwin) \
+		cd $(BUILDDIR)/binutils-src/zlib && \
+	    sed -i.bak 's/defined(MACOS) || defined(TARGET_OS_MAC)/defined(MACOS)/' zutil.h && \
+	    rm -f zutil.h.bak ;; esac
+	cd $(BUILDDIR)/binutils-src/bfd && \
+	    sed -i.bak 's/development=.*/development=false/' development.sh && \
+	    rm -f development.sh.bak
 	touch $(BUILDDIR)/.binutils.src
 
 $(BUILDDIR)/.binutils.build: $(BUILDDIR)/.binutils.src
@@ -99,7 +106,7 @@ $(DISTDIR)/$(MPC_DIST).tar.gz:
 
 # GCC for IA16
 
-GCC_VER=43408af9d4127b884ab39dcff6a829e86008e587
+GCC_VER=ca893320926dc93552390b892a202e9373d040c0
 GCC_DIST=gcc-ia16-$(GCC_VER)
 
 $(DISTDIR)/$(GCC_DIST).tar.gz:
@@ -130,12 +137,30 @@ $(BUILDDIR)/.gcc.src: $(DISTDIR)/$(GCC_DIST).tar.gz \
 	cd $(BUILDDIR)/gcc-src && ln -s $(MPFR_DIST) mpfr
 	cd $(BUILDDIR)/gcc-src && tar -xzf $(DISTDIR)/$(MPC_DIST).tar.gz
 	cd $(BUILDDIR)/gcc-src && ln -s $(MPC_DIST) mpc
+	case `uname -s` in Darwin) \
+		cd $(BUILDDIR)/gcc-src/zlib && \
+	    sed -i.bak 's/defined(MACOS) || defined(TARGET_OS_MAC)/defined(MACOS)/' zutil.h && \
+	    rm -f zutil.h.bak ;; esac
+	cd $(BUILDDIR)/gcc-src/gcc && \
+	    sed -i.bak 's/heapb->min->compare (heapa->min)/heapb->m_min->compare (heapa->m_min)/' fibonacci_heap.h && \
+	    rm -f fibonacci_heap.h.bak
+	case `uname -s`-`uname -m` in Darwin-arm64) \
+		cd $(BUILDDIR)/gcc-src/gcc/config && \
+	    sed -i.bak 's/aligned (4096)/aligned (16384)/' host-darwin.c && \
+	    rm -f host-darwin.c.bak && \
+		cd $(BUILDDIR)/gcc-src/gcc && \
+	    awk '/i\[34567\]86-\*-darwin\* \| x86_64-\*-darwin\*\)/{print "  aarch64-*-darwin* | arm-*-darwin*)"; print "    out_host_hook_obj=\"$${out_host_hook_obj} host-aarch64-darwin.o\""; print "    host_xmake_file=\"$${host_xmake_file} aarch64/x-darwin\""; print "    ;;"} {print}' config.host > config.host.tmp && \
+	    mv config.host.tmp config.host && \
+		printf 'host-aarch64-darwin.o : $$(srcdir)/config/aarch64/host-aarch64-darwin.c\n\t$$(COMPILE) $$<\n\t$$(POSTCOMPILE)\n' \
+		    > $(BUILDDIR)/gcc-src/gcc/config/aarch64/x-darwin && \
+		printf '/* aarch64-darwin host-specific hook definitions. */\n#include "config.h"\n#include "system.h"\n#include "coretypes.h"\n#include "hosthooks.h"\n#include "hosthooks-def.h"\n#include "config/host-darwin.h"\nconst struct host_hooks host_hooks = HOST_HOOKS_INITIALIZER;\n' \
+		    > $(BUILDDIR)/gcc-src/gcc/config/aarch64/host-aarch64-darwin.c ;; esac
 	touch $(BUILDDIR)/.gcc.src
 
 $(BUILDDIR)/.gcc.build: $(BUILDDIR)/.gcc.src $(BUILDDIR)/.binutils.build
 	cd $(BUILDDIR) && rm -rf gcc-build
 	mkdir $(BUILDDIR)/gcc-build
-	cd $(BUILDDIR)/gcc-build && ../gcc-src/configure --target=ia16-elf --prefix="$(CROSSDIR)" --without-headers --enable-languages=c --disable-libssp --without-isl
+	cd $(BUILDDIR)/gcc-build && LC_ALL=C ../gcc-src/configure --target=ia16-elf --prefix="$(CROSSDIR)" --without-headers --enable-languages=c --disable-libssp --without-isl --disable-nls
 	# If there are any obsolete multilib directories (which are no longer
 	# used) in the installation directory, remove them, so that they do
 	# not clutter up the installation directory.  This is a bit of a hack.
@@ -145,7 +170,7 @@ $(BUILDDIR)/.gcc.build: $(BUILDDIR)/.gcc.src $(BUILDDIR)/.binutils.build
 	       $(CROSSDIR)/lib/gcc/ia16-elf/6.3.0/regparmcall/size \
 	       $(CROSSDIR)/lib/gcc/ia16-elf/6.3.0/regparmcall/any_186/size
 	# Now build.
-	$(MAKE) -C $(BUILDDIR)/gcc-build $(PARALLEL)
+	LC_ALL=C $(MAKE) -C $(BUILDDIR)/gcc-build $(PARALLEL)
 	touch $(BUILDDIR)/.gcc.build
 
 $(CROSSDIR)/.gcc.install: $(BUILDDIR)/.gcc.build