--- a/Makefile	Wed Sep 01 10:03:45 2021 +0300
+++ b/Makefile	Wed Sep 01 10:06:10 2021 +0300
@@ -116,6 +116,8 @@
 
 LATEX2PDF := pdflatex
 
+PYTHON ?= python3
+
 ifeq '$(ANKI_PY_DIR)' ''
   ANKI_PY_DIR := /usr/share/anki
 endif
@@ -556,7 +558,7 @@
 
 .PHONY: freq
 freq: dist/wordlist/gadict.list py/gadict_freq.py $(FREQ_DEP) $(BUILD_SCRIPTS)
-	python3 -B py/gadict_freq.py +b:dist/wordlist/gadict.list $(FREQ_FILTER)
+	$(PYTHON) -B py/gadict_freq.py +b:dist/wordlist/gadict.list $(FREQ_FILTER)
 
 .PHONY: missing
 missing: missing-words missing-stat
@@ -564,39 +566,39 @@
 .PHONY: missing-words
 missing-words: dist/wordlist/gadict.list $(FREQ_DEP) $(BUILD_SCRIPTS)
 	@echo ===== VOA =====
-	python3 -B py/gadict_freq.py -b:dist/wordlist/gadict.list +b:dist/wordlist/voa.list
+	$(PYTHON) -B py/gadict_freq.py -b:dist/wordlist/gadict.list +b:dist/wordlist/voa.list
 	@echo ===== GSL =====
-	python3 -B py/gadict_freq.py -b:dist/wordlist/gadict.list +f:wordlist/gsl.freq
+	$(PYTHON) -B py/gadict_freq.py -b:dist/wordlist/gadict.list +f:wordlist/gsl.freq
 	@echo ===== AWL =====
-	python3 -B py/gadict_freq.py -b:dist/wordlist/gadict.list +f:wordlist/awl.freq
+	$(PYTHON) -B py/gadict_freq.py -b:dist/wordlist/gadict.list +f:wordlist/awl.freq
 	@echo ===== NGSL =====
-	python3 -B py/gadict_freq.py -b:dist/wordlist/gadict.list +f:wordlist/ngsl.freq
+	$(PYTHON) -B py/gadict_freq.py -b:dist/wordlist/gadict.list +f:wordlist/ngsl.freq
 	@echo ===== NAWL =====
-	python3 -B py/gadict_freq.py -b:dist/wordlist/gadict.list +f:wordlist/nawl.freq
+	$(PYTHON) -B py/gadict_freq.py -b:dist/wordlist/gadict.list +f:wordlist/nawl.freq
 	@echo ===== BSL =====
-	python3 -B py/gadict_freq.py -b:dist/wordlist/gadict.list +b:wordlist/bsl.var
+	$(PYTHON) -B py/gadict_freq.py -b:dist/wordlist/gadict.list +b:wordlist/bsl.var
 	@echo ===== TSL =====
-	python3 -B py/gadict_freq.py -b:dist/wordlist/gadict.list +b:wordlist/tsl.var
+	$(PYTHON) -B py/gadict_freq.py -b:dist/wordlist/gadict.list +b:wordlist/tsl.var
 	@echo ===== KET =====
-	python3 -B py/gadict_freq.py -b:dist/wordlist/gadict.list +b:wordlist/ket.var
+	$(PYTHON) -B py/gadict_freq.py -b:dist/wordlist/gadict.list +b:wordlist/ket.var
 	@echo ===== PET =====
-	python3 -B py/gadict_freq.py -b:dist/wordlist/gadict.list +b:wordlist/pet.var
+	$(PYTHON) -B py/gadict_freq.py -b:dist/wordlist/gadict.list +b:wordlist/pet.var
 
 .PHONY: missing-speakout
 missing-speakout: dist/wordlist/gadict.list $(FREQ_DEP) $(BUILD_SCRIPTS)
 	@echo ===== so1 =====
-	python3 -B py/gadict_freq.py -b:dist/wordlist/gadict.list +b:so1.list | tee so1.miss
+	$(PYTHON) -B py/gadict_freq.py -b:dist/wordlist/gadict.list +b:so1.list | tee so1.miss
 	@echo ===== so2 =====
-	python3 -B py/gadict_freq.py -b:dist/wordlist/gadict.list +b:so2.list | tee so2.miss
+	$(PYTHON) -B py/gadict_freq.py -b:dist/wordlist/gadict.list +b:so2.list | tee so2.miss
 	@echo ===== so3 =====
-	python3 -B py/gadict_freq.py -b:dist/wordlist/gadict.list +b:so3.list | tee so3.miss
+	$(PYTHON) -B py/gadict_freq.py -b:dist/wordlist/gadict.list +b:so3.list | tee so3.miss
 	@echo ===== so4 =====
-	python3 -B py/gadict_freq.py -b:dist/wordlist/gadict.list +b:so4.list | tee so4.miss
+	$(PYTHON) -B py/gadict_freq.py -b:dist/wordlist/gadict.list +b:so4.list | tee so4.miss
 
 define stat-cmd
 { \
 stat() { \
-  lack=`python3 -B py/gadict_freq.py -b:dist/wordlist/gadict.list $$2:$$3 | wc -l`; \
+  lack=`$(PYTHON) -B py/gadict_freq.py -b:dist/wordlist/gadict.list $$2:$$3 | wc -l`; \
   total=`grep -v '^[ 	]' $$3 | wc -l`; \
   cover=$$((total - lack)); \
   printf "   %4s %5s %5s %4s\n" $$1 $$cover $$total $$lack; \
@@ -622,7 +624,7 @@
 	@${stat-cmd}
 
 dist/wordlist/%.list: %.gadict py/gadict_headwords.py $(BUILD_SCRIPTS) | dist/wordlist/
-	python3 -B py/gadict_headwords.py  $< $@
+	$(PYTHON) -B py/gadict_headwords.py  $< $@
 
 dist/wordlist/gsl.var: $(GSL_BASEWORD) | dist/wordlist/
 	cat $(GSL_BASEWORD) >$@
@@ -631,7 +633,7 @@
 	cat $(NGSL_BASEWORD) >$@
 
 dist/wordlist/voa.list: gadict_voa.gadict py/gadict_headwords.py $(MAKEFILE_LIST) | dist/wordlist/
-	python3 -B py/gadict_headwords.py gadict_voa.gadict >$@
+	$(PYTHON) -B py/gadict_headwords.py gadict_voa.gadict >$@
 
 dist/wordlist/:
 	mkdir -p $@
@@ -669,22 +671,22 @@
 # -B  suppress __pycache__ dir
 
 dist/dictd/gadict.c5: gadict.gadict $(FREQLIST_DEP) py/gadict.py py/gadict_c5.py $(MAKEFILE_LIST) | dist/dictd/
-	LC_ALL=en_US.utf8 python3 -B py/gadict_c5.py $(FREQLIST_OPT)  $< $@
+	LC_ALL=en_US.utf8 $(PYTHON) -B py/gadict_c5.py $(FREQLIST_OPT)  $< $@
 	echo "gadict En-Ru+Uk"> dist/dictd/gadict.c5.name
 
 dist/dictd/gadict_en-ru.c5: gadict.gadict py/gadict.py py/gadict_c5.py $(MAKEFILE_LIST) | dist/dictd/
-	LC_ALL=en_US.utf8 python3 -B py/gadict_c5.py  $< $@ -lang:ru
+	LC_ALL=en_US.utf8 $(PYTHON) -B py/gadict_c5.py  $< $@ -lang:ru
 	echo "gadict En-Ru"> dist/dictd/gadict_en-ru.c5.name
 
 dist/dictd/gadict_en-uk.c5: gadict.gadict py/gadict.py py/gadict_c5.py $(MAKEFILE_LIST) | dist/dictd/
-	LC_ALL=en_US.utf8 python3 -B py/gadict_c5.py  $< $@ -lang:uk
+	LC_ALL=en_US.utf8 $(PYTHON) -B py/gadict_c5.py  $< $@ -lang:uk
 	echo "gadict En-Uk"> dist/dictd/gadict_en-uk.c5.name
 
 dist/dictd/gadict_voa.c5: gadict_voa.gadict py/gadict.py py/gadict_c5.py $(MAKEFILE_LIST) | dist/dictd/
-	LC_ALL=en_US.utf8 python3 -B py/gadict_c5.py  $< $@ -lang:en
+	LC_ALL=en_US.utf8 $(PYTHON) -B py/gadict_c5.py  $< $@ -lang:en
 
 dist/dictd/%.c5: %.gadict py/gadict.py py/gadict_c5.py $(MAKEFILE_LIST) | dist/dictd/
-	LC_ALL=en_US.utf8 python3 -B py/gadict_c5.py  $< $@
+	LC_ALL=en_US.utf8 $(PYTHON) -B py/gadict_c5.py  $< $@
 
 dist/dictd/:
 	mkdir -p $@
@@ -703,32 +705,32 @@
 
 # Specific rules (due to renames or other customization).
 dist/anki/gadict.apkg: gadict.gadict $(GADICT_DEL_FILE) py/gadict.py py/gadict_srs_anki.py $(FREQLIST_DEP) $(MAKEFILE_LIST) | dist/anki/
-	PYTHONPATH=$(ANKI_PY_DIR): LC_ALL=en_US.utf8 python3 -B py/gadict_srs_anki.py -name="gadict_en-ru+uk" -rich $(GADICT_DEL_OPT) $(FREQLIST_OPT) $< $@
+	PYTHONPATH=$(ANKI_PY_DIR): LC_ALL=en_US.utf8 $(PYTHON) -B py/gadict_srs_anki.py -name="gadict_en-ru+uk" -rich $(GADICT_DEL_OPT) $(FREQLIST_OPT) $< $@
 
 dist/anki/gadict_voa.apkg: gadict_voa.gadict py/gadict.py py/gadict_srs_anki.py $(VOA_FREQLIST_DEP) $(MAKEFILE_LIST) | dist/anki/
-	PYTHONPATH=$(ANKI_PY_DIR): LC_ALL=en_US.utf8 python3 -B py/gadict_srs_anki.py -name="gadict_voa" $(VOA_FREQLIST_OPT) $< $@
+	PYTHONPATH=$(ANKI_PY_DIR): LC_ALL=en_US.utf8 $(PYTHON) -B py/gadict_srs_anki.py -name="gadict_voa" $(VOA_FREQLIST_OPT) $< $@
 
 dist/anki/%.apkg: %.gadialog py/gadialog_srs_anki.py $(MAKEFILE_LIST) | dist/anki/
-	PYTHONPATH=$(ANKI_PY_DIR): LC_ALL=en_US.utf8 python3 -B py/gadialog_srs_anki.py -name="$*" $< $@
+	PYTHONPATH=$(ANKI_PY_DIR): LC_ALL=en_US.utf8 $(PYTHON) -B py/gadialog_srs_anki.py -name="$*" $< $@
 
 dist/anki/%.apkg: %.gaphrase py/gaphrase_srs_anki.py $(MAKEFILE_LIST) | dist/anki/
-	PYTHONPATH=$(ANKI_PY_DIR): LC_ALL=en_US.utf8 python3 -B py/gaphrase_srs_anki.py -name="$*" $< $@
+	PYTHONPATH=$(ANKI_PY_DIR): LC_ALL=en_US.utf8 $(PYTHON) -B py/gaphrase_srs_anki.py -name="$*" $< $@
 
 # General rules.
 dist/anki/%.apkg: %.gadict %.del py/gadict.py py/gadict_srs_anki.py $(FREQLIST_DEP) $(MAKEFILE_LIST) | dist/anki/
-	PYTHONPATH=$(ANKI_PY_DIR): LC_ALL=en_US.utf8 python3 -B py/gadict_srs_anki.py -name=$* -rich -delfile=$*.del $(FREQLIST_OPT) $< $@
+	PYTHONPATH=$(ANKI_PY_DIR): LC_ALL=en_US.utf8 $(PYTHON) -B py/gadict_srs_anki.py -name=$* -rich -delfile=$*.del $(FREQLIST_OPT) $< $@
 
 dist/anki/%.apkg: %.gadict py/gadict.py py/gadict_srs_anki.py $(FREQLIST_DEP) $(MAKEFILE_LIST) | dist/anki/
-	PYTHONPATH=$(ANKI_PY_DIR): LC_ALL=en_US.utf8 python3 -B py/gadict_srs_anki.py -name=$* -rich $(FREQLIST_OPT) $< $@
+	PYTHONPATH=$(ANKI_PY_DIR): LC_ALL=en_US.utf8 $(PYTHON) -B py/gadict_srs_anki.py -name=$* -rich $(FREQLIST_OPT) $< $@
 
 .PHONY: tab
 tab: $(SRS_TAB_FILES)
 
 dist/srs/gadict.tab.txt: gadict.gadict py/gadict.py py/gadict_srs_tab.py $(MAKEFILE_LIST) | dist/srs/
-	python3 -B py/gadict_srs_tab.py  $< $@ -lang:ru,uk
+	$(PYTHON) -B py/gadict_srs_tab.py  $< $@ -lang:ru,uk
 
 dist/srs/%.tab.txt: %.gadict py/gadict.py py/gadict_srs_tab.py $(MAKEFILE_LIST) | dist/srs/
-	python3 -B py/gadict_srs_tab.py  $< $@
+	$(PYTHON) -B py/gadict_srs_tab.py  $< $@
 
 dist/anki/ dist/srs/:
 	mkdir -p $@
@@ -737,13 +739,13 @@
 html: $(DICT_HTML_FILES)
 
 dist/html/gadict_voa.html: gadict_voa.gadict py/gadict.py py/gadict_html.py $(VOA_FREQLIST_DEP) $(MAKEFILE_LIST) | dist/html/
-	python3 -B py/gadict_html.py $(VOA_FREQLIST_OPT) $< $@
+	$(PYTHON) -B py/gadict_html.py $(VOA_FREQLIST_OPT) $< $@
 
 dist/html/%.html: %.gadict py/gadict.py py/gadict_html.py $(FREQLIST_DEP) $(MAKEFILE_LIST) | dist/html/
-	python3 -B py/gadict_html.py $(FREQLIST_OPT) $< $@
+	$(PYTHON) -B py/gadict_html.py $(FREQLIST_OPT) $< $@
 
 dist/html/gadialog.html: gadialog.gadialog py/gadialog.py py/gadialog_html.py | dist/html/
-	python3 -B py/gadialog_html.py $< $@
+	$(PYTHON) -B py/gadialog_html.py $< $@
 
 dist/html/:
 	mkdir -p $@
@@ -877,7 +879,7 @@
 #   $ sudo apt-get install python3-enchant hunspell-en-us hunspell-en-gb hunspell-en-au hunspell-en-ca
 .PHONY: check
 check:
-	python3 -B py/gadict_spellcheck.py gadict.gadict
+	$(PYTHON) -B py/gadict_spellcheck.py gadict.gadict
 
 ################################################################
 # Clean targets.