diff --git a/.github/workflows/fpga-pm5.yml b/.github/workflows/fpga-pm5.yml
index 1a0f88b5f..dcac7aadd 100644
--- a/.github/workflows/fpga-pm5.yml
+++ b/.github/workflows/fpga-pm5.yml
@@ -36,17 +36,10 @@ jobs:
           # front of PATH itself, so nothing else needs to be exported
           echo "OSS_CAD_SUITE=$RUNNER_TEMP/oss-cad-suite" >> "$GITHUB_ENV"
 
-      - name: Show the toolchain
-        run: |
-          set -euo pipefail
-          # the same resolution the build uses, then the versions for the log
-          make -C fpga -f proxmark5_fpga.mk check-tools
-          set +u
-          source "$OSS_CAD_SUITE/environment"
-          set -u
-          yosys -V
-          nextpnr-himbaechel --version
-          python3 -c "import apycula; print('apycula:', apycula.__file__)"
+      # Runs the real tools through the same environment the build uses, so a
+      # suite that cannot run fails here instead of half way through the build.
+      - name: Check the toolchain
+        run: make -C fpga -f proxmark5_fpga.mk smoke
 
       # Place and route fails the job on a timing violation, so this does not
       # only prove the design still elaborates.
diff --git a/fpga/proxmark5_fpga.mk b/fpga/proxmark5_fpga.mk
index 909a99a87..8a190aee1 100644
--- a/fpga/proxmark5_fpga.mk
+++ b/fpga/proxmark5_fpga.mk
@@ -43,12 +43,22 @@ PM5_OUT  = $(PREFIX)build_$(PM5_NAME)
 
 # The oss-cad-suite launchers need their root, and both bin/ and lib/ on PATH
 # (lib/ carries the shared libraries), otherwise they exit without a message.
-# The suite bundles its own python, named per platform. With OSS_CAD_SUITE
-# unset everything comes from PATH instead, which is what sourcing the suite's
-# environment script gives you.
+# The suite is laid out per platform, and each of its own environment scripts
+# says what to put where. On Windows the shared libraries sit in lib/ and are
+# found through PATH, as environment.bat does. Everywhere else they are found by
+# the tools themselves, and adding lib/ to PATH or LD_LIBRARY_PATH makes yosys
+# load the suite's libstdc++ instead of the system one and segfault at startup.
+# With OSS_CAD_SUITE unset the tools come from PATH, which is what sourcing the
+# suite's environment gives you.
 ifneq ($(OSS_CAD_SUITE),)
-OC_PYTHON = $(firstword $(wildcard $(OSS_CAD_SUITE)/lib/python3.exe $(OSS_CAD_SUITE)/py3bin/python3 $(OSS_CAD_SUITE)/lib/python3 $(OSS_CAD_SUITE)/bin/python3) python3)
-OC_ENV    = YOSYSHQ_ROOT="$(OSS_CAD_SUITE)/" PATH="$(OSS_CAD_SUITE)/bin:$(OSS_CAD_SUITE)/lib:$$PATH" LD_LIBRARY_PATH="$(OSS_CAD_SUITE)/lib:$$LD_LIBRARY_PATH" PYTHON_EXECUTABLE="$(OC_PYTHON)"
+ifneq ($(wildcard $(OSS_CAD_SUITE)/lib/python3.exe),)
+OC_PATH   = $(OSS_CAD_SUITE)/bin:$(OSS_CAD_SUITE)/lib
+OC_PYTHON = $(OSS_CAD_SUITE)/lib/python3.exe
+else
+OC_PATH   = $(OSS_CAD_SUITE)/bin:$(OSS_CAD_SUITE)/py3bin
+OC_PYTHON = $(firstword $(wildcard $(OSS_CAD_SUITE)/py3bin/python3 $(OSS_CAD_SUITE)/bin/python3) python3)
+endif
+OC_ENV = YOSYSHQ_ROOT="$(OSS_CAD_SUITE)/" PATH="$(OC_PATH):$$PATH" PYTHON_EXECUTABLE="$(OC_PYTHON)"
 else
 OC_ENV    =
 OC_PYTHON = python3
@@ -57,7 +67,7 @@ endif
 PM5_BUILD_HDL = $(addprefix ../,$(PM5_HDL))
 PM5_DEFS      = $(foreach d,$(PM5_DEFINES),-D $(d))
 
-.PHONY: all clean help check-tools $(PM5_NAME)
+.PHONY: all clean help check-tools smoke $(PM5_NAME)
 
 all: $(PM5_NAME)
 
@@ -122,6 +132,15 @@ check-tools:
 		exit 1; \
 	fi
 
+# Compile a two line design through the same toolchain and environment the
+# build uses, so a suite that cannot run fails here with a clear message
+# instead of half way through the build.
+smoke: | check-tools $(PM5_OUT)
+	$(Q)$(OC_ENV) yosys -V
+	$(Q)printf '%s\n' "module smoke(input a, output b);" "    assign b = ~a;" "endmodule" > $(PM5_OUT)/smoke.v
+	$(Q)cd $(PM5_OUT) && $(OC_ENV) yosys -q -p "read_verilog smoke.v; synth_gowin -json smoke.json"
+	$(Q)test -s $(PM5_OUT)/smoke.json && echo "[=] SMOKE ok"
+
 # ALWAYS have some hardcoded text after $(PREFIX) to avoid rm -rf * or rm -rf /* situations if PREFIX is incorrectly set to empty "" or just "/"
 clean:
 	$(Q)$(RMDIR) $(PREFIX)build_$(PM5_NAME)