diff --git a/Makefile b/Makefile
index a24f19b6a..845a97b50 100644
--- a/Makefile
+++ b/Makefile
@@ -147,9 +147,9 @@ $(info $(subst $$--$$,$(newline),$(shell sed 's,^,[Makefile.conf] ,; s,$$,$$--$$
 include Makefile.conf
 endif
 
+PYTHON_EXECUTABLE := $(shell if python3 -c ""; then echo "python3"; else echo "python"; fi)
 ifeq ($(ENABLE_PYOSYS),1)
 PYTHON_VERSION_TESTCODE := "import sys;t='{v[0]}.{v[1]}'.format(v=list(sys.version_info[:2]));print(t)"
-PYTHON_EXECUTABLE := $(shell if python3 -c ""; then echo "python3"; else echo "python"; fi)
 PYTHON_VERSION := $(shell $(PYTHON_EXECUTABLE) -c ""$(PYTHON_VERSION_TESTCODE)"")
 PYTHON_MAJOR_VERSION := $(shell echo $(PYTHON_VERSION) | cut -f1 -d.)
 PYTHON_PREFIX := $(shell $(PYTHON_EXECUTABLE)-config --prefix)
diff --git a/passes/pmgen/Makefile.inc b/passes/pmgen/Makefile.inc
index 366c37943..145d2ebf9 100644
--- a/passes/pmgen/Makefile.inc
+++ b/passes/pmgen/Makefile.inc
@@ -1,5 +1,5 @@
 %_pm.h: passes/pmgen/pmgen.py %.pmg
-	$(P) mkdir -p passes/pmgen && python3 $< -o $@ -p $(subst _pm.h,,$(notdir $@)) $(filter-out $<,$^)
+	$(P) mkdir -p passes/pmgen && $(PYTHON_EXECUTABLE) $< -o $@ -p $(subst _pm.h,,$(notdir $@)) $(filter-out $<,$^)
 
 # --------------------------------------
 
@@ -38,7 +38,7 @@ PEEPOPT_PATTERN += passes/pmgen/peepopt_muldiv.pmg
 PEEPOPT_PATTERN += passes/pmgen/peepopt_dffmux.pmg
 
 passes/pmgen/peepopt_pm.h: passes/pmgen/pmgen.py $(PEEPOPT_PATTERN)
-	$(P) mkdir -p passes/pmgen && python3 $< -o $@ -p peepopt $(filter-out $<,$^)
+	$(P) mkdir -p passes/pmgen && $(PYTHON_EXECUTABLE) $< -o $@ -p peepopt $(filter-out $<,$^)
 
 # --------------------------------------
 
diff --git a/techlibs/common/Makefile.inc b/techlibs/common/Makefile.inc
index 6c0a4fe66..a42f63128 100644
--- a/techlibs/common/Makefile.inc
+++ b/techlibs/common/Makefile.inc
@@ -9,12 +9,12 @@ GENFILES += techlibs/common/simcells_help.inc
 
 techlibs/common/simlib_help.inc: techlibs/common/cellhelp.py techlibs/common/simlib.v
 	$(Q) mkdir -p techlibs/common
-	$(P) python3 $^ > $@.new
+	$(P) $(PYTHON_EXECUTABLE) $^ > $@.new
 	$(Q) mv $@.new $@
 
 techlibs/common/simcells_help.inc: techlibs/common/cellhelp.py techlibs/common/simcells.v
 	$(Q) mkdir -p techlibs/common
-	$(P) python3 $^ > $@.new
+	$(P) $(PYTHON_EXECUTABLE) $^ > $@.new
 	$(Q) mv $@.new $@
 
 kernel/register.o: techlibs/common/simlib_help.inc techlibs/common/simcells_help.inc
diff --git a/techlibs/ecp5/Makefile.inc b/techlibs/ecp5/Makefile.inc
index 5832d07ee..46463f510 100644
--- a/techlibs/ecp5/Makefile.inc
+++ b/techlibs/ecp5/Makefile.inc
@@ -27,12 +27,12 @@ EXTRA_OBJS += techlibs/ecp5/brams_init.mk techlibs/ecp5/brams_connect.mk
 
 techlibs/ecp5/brams_init.mk: techlibs/ecp5/brams_init.py
 	$(Q) mkdir -p techlibs/ecp5
-	$(P) python3 $<
+	$(P) $(PYTHON_EXECUTABLE) $<
 	$(Q) touch $@
 
 techlibs/ecp5/brams_connect.mk: techlibs/ecp5/brams_connect.py
 	$(Q) mkdir -p techlibs/ecp5
-	$(P) python3 $<
+	$(P) $(PYTHON_EXECUTABLE) $<
 	$(Q) touch $@
 
 
diff --git a/techlibs/ice40/Makefile.inc b/techlibs/ice40/Makefile.inc
index 3c33fcb06..31478e80e 100644
--- a/techlibs/ice40/Makefile.inc
+++ b/techlibs/ice40/Makefile.inc
@@ -14,7 +14,7 @@ EXTRA_OBJS += techlibs/ice40/brams_init.mk
 
 techlibs/ice40/brams_init.mk: techlibs/ice40/brams_init.py
 	$(Q) mkdir -p techlibs/ice40
-	$(P) python3 $<
+	$(P) $(PYTHON_EXECUTABLE) $<
 	$(Q) touch techlibs/ice40/brams_init.mk
 
 techlibs/ice40/brams_init1.vh: techlibs/ice40/brams_init.mk
diff --git a/techlibs/xilinx/Makefile.inc b/techlibs/xilinx/Makefile.inc
index 0ae67d9e7..1e59f0a1b 100644
--- a/techlibs/xilinx/Makefile.inc
+++ b/techlibs/xilinx/Makefile.inc
@@ -13,7 +13,7 @@ EXTRA_OBJS += techlibs/xilinx/brams_init.mk
 
 techlibs/xilinx/brams_init.mk: techlibs/xilinx/brams_init.py
 	$(Q) mkdir -p techlibs/xilinx
-	$(P) python3 $<
+	$(P) $(PYTHON_EXECUTABLE) $<
 	$(Q) touch $@
 
 techlibs/xilinx/brams_init_36.vh: techlibs/xilinx/brams_init.mk