diff --git a/proto-opencl/host.c b/proto-opencl/host.c
index 4cfb2cb02..541958450 100644
--- a/proto-opencl/host.c
+++ b/proto-opencl/host.c
@@ -11,6 +11,10 @@
 //
 // Build: see README.md (macOS -framework OpenCL, Linux -lOpenCL, Windows cl.exe + OpenCL.lib), or build.sh / build.bat.
 
+#if !defined(_WIN32) && !defined(__APPLE__) && !defined(_POSIX_C_SOURCE)
+#define _POSIX_C_SOURCE 200809L   /* clock_gettime and strtok_r under -std=c99 on Linux (glibc hides them without it; the kit build of 7 October 2026) */
+#define _DEFAULT_SOURCE
+#endif
 #define _CRT_SECURE_NO_WARNINGS
 #define CL_TARGET_OPENCL_VERSION 120
 #define CL_USE_DEPRECATED_OPENCL_1_2_APIS
diff --git a/tools/class-v5/kits-remote.sh b/tools/class-v5/kits-remote.sh
index 2223ea780..7618207e9 100755
--- a/tools/class-v5/kits-remote.sh
+++ b/tools/class-v5/kits-remote.sh
@@ -49,7 +49,9 @@ g++ -std=c++17 -O2 -Wall -Wextra -I proto-cuda/nvrtc -I /usr/local/cuda/include
 step windows-cuda-worker
 x86_64-w64-mingw32-g++ -std=c++17 -O2 -Wall -Wextra -static -I proto-cuda/nvrtc -I /usr/local/cuda/include -o \$S/bin/windows/igneum-worker-cuda.exe proto-cuda/nvrtc/worker.cpp 2> \$T/cuda-win.log && x86_64-w64-mingw32-strip \$S/bin/windows/igneum-worker-cuda.exe || { fail "windows cuda worker"; head -20 \$T/cuda-win.log; }
 step windows-opencl-worker
-x86_64-w64-mingw32-gcc -std=c99 -O2 -Wall -Wextra -Wno-stringop-truncation -Wno-format-truncation -static -DIGNEUM_CL_DYNAMIC -DCL_TARGET_OPENCL_VERSION=120 -I /usr/include -I proto-cuda/packs/igneum-devnet-v4-epoch0 -DIGNEUM_KERNEL_PATH='"kernel_bound.cl"' -o \$S/bin/windows/igneum-worker-opencl.exe proto-opencl/host.c 2> \$T/cl-win.log && x86_64-w64-mingw32-strip \$S/bin/windows/igneum-worker-opencl.exe || { fail "windows opencl worker"; head -20 \$T/cl-win.log; }
+# the Khronos CL headers alone (never -I /usr/include: that puts glibc's stdint.h ahead of mingw's)
+mkdir -p \$T/inc && cp -r /usr/include/CL \$T/inc/
+x86_64-w64-mingw32-gcc -std=c99 -O2 -Wall -Wextra -Wno-stringop-truncation -Wno-format-truncation -static -DIGNEUM_CL_DYNAMIC -DCL_TARGET_OPENCL_VERSION=120 -I \$T/inc -I proto-cuda/packs/igneum-devnet-v4-epoch0 -DIGNEUM_KERNEL_PATH='"kernel_bound.cl"' -o \$S/bin/windows/igneum-worker-opencl.exe proto-opencl/host.c 2> \$T/cl-win.log && x86_64-w64-mingw32-strip \$S/bin/windows/igneum-worker-opencl.exe || { fail "windows opencl worker"; head -20 \$T/cl-win.log; }
 if [ $SKIP_EMU = 0 ]; then
   step emu-check-v5
   # the CPU emulation (proto-cuda/nvrtc/emu/test.sh's build) with pack A = the class v5 pack and pack B = the v4 control
@@ -65,6 +67,7 @@ if [ $SKIP_EMU = 0 ]; then
     grep -E '^check PASS|self-test|FAIL|error' \$T/emu-check.log | cut -c1-400
   fi
 fi
+if [ \$rc != 0 ]; then echo "KIT not written: a step failed (rc \$rc)"; mkdir -p /srv/builds/_log/v5-class/kits-$STAMP && cp \$T/*.log /srv/builds/_log/v5-class/kits-$STAMP/; echo "LOGS /srv/builds/_log/v5-class/kits-$STAMP"; rm -rf \$T; exit 1; fi
 step stage
 for p in v4-genesis v5-genesis v5-dn3-epoch0; do mkdir -p \$S/packs/\$p; cp proto-cuda/packs-ca3-v5/\$p/* \$S/packs/\$p/; done
 cp proto-cuda/nvrtc/worker.cpp proto-cuda/nvrtc/packfile.h proto-cuda/nvrtc/cuda_api.h proto-opencl/host.c proto-opencl/cl_dynamic.h proto-newpow/class-v5/bench.cu proto-newpow/class-v5/run.sh proto-metal/packbench.swift \$S/src/
@@ -105,8 +108,10 @@ echo "LOGS /srv/builds/_log/v5-class/kits-$STAMP"
 rm -rf \$T
 ( exit \$rc )
 EOF2
+set +e
 BR_KIND=build BR_COMMAND="class v5 kits (packfile-test, emu --check v5, Linux and Windows workers, kit zip)" BR_TARGET="x86_64-linux+windows" BR_ARTEFACTS="" \
-  bs_remote_run "$WT" "$BS_WT class-v5 kits" "$CMD" 2>&1 | tee "/tmp/v5-kits-$STAMP.log" | grep -E '^(STEP|FAIL|KIT|BIN|LOGS|check PASS|self-test|packfile-test|emu:|     v5|build-remote: RESULT)' || true
-rc=${PIPESTATUS[0]}
+  bs_remote_run "$WT" "$BS_WT class-v5 kits" "$CMD" 2>&1 | tee "/tmp/v5-kits-$STAMP.log" | grep -E '^(STEP|FAIL|KIT|BIN|LOGS|check PASS|self-test|packfile-test|emu:|     v5|build-remote: RESULT)'
+rc=${PIPESTATUS[0]}   # the remote runner's status, read before anything else runs (the first run read `true`'s and called a failed build built)
+set -e
 bs_wt_unlock
 [ "$rc" = 0 ] && bs_log "class v5 kits built: $ZIP" || bs_die "class v5 kits FAILED (rc $rc); full log /tmp/v5-kits-$STAMP.log"