diff --git a/shell-completion/Makefile b/shell-completion/Makefile
index 10f64b171..abdf75366 100644
--- a/shell-completion/Makefile
+++ b/shell-completion/Makefile
@@ -1,30 +1,34 @@
-
-.PHONY: command-options clean
+# Setting the number of job runners like this in the makefile only works in
+# GNU Make 4.3 or later. Older versions will require that either an env
+# variable be set before running or command line flag be passed at runtime to
+# get parallel jobs.
+MAKEFLAGS += --jobs=$(shell nproc 2>/dev/null || printf 8)
 
 all: hledger-completion.bash
 
-hledger-completion.bash: hledger-completion.bash.m4 commands-list.txt query-filters.txt generic-options.txt command-options
+COMMANDS := $(sort $(shell hledger | ./output-commands.sh | grep -v ^hledger | sort -u) ui web api)
+CMDOPTFILES := $(foreach CMD,$(COMMANDS),options-$(CMD).txt)
+
+hledger-completion.bash: hledger-completion.bash.m4 commands.txt commands-list.txt query-filters.txt generic-options.txt $(CMDOPTFILES)
 	m4 hledger-completion.bash.m4 > $@
 
 generic-options.txt:
 	hledger -h | ./output-options.sh | sort -u > $@
 
 commands.txt:
-	hledger | ./output-commands.sh | grep -v ^hledger | sort -u > $@
-	echo ui  >> $@
-	echo web >> $@
-	echo api >> $@
+	printf "%s\n" $(COMMANDS) > $@
 
-commands-list.txt: commands.txt
-	paste -sd, $^ | tr -d '\n' > $@
+commands-list.txt:
+	printf "%s,"  $(COMMANDS) | sed 's/,$$//' > $@
 
 #query-filters.txt:
 	# The query filters are hard to extract!
 	# hledger help --cat hledger | sed -n '/^QUERIES/,/^[A-Z]/p'
 
-command-options: commands.txt
-	parallel -j8 'hledger {} -h | ./output-options.sh {} | sort -u > options-{}.txt' < commands.txt
+options-%.txt:
+	hledger $* -h | ./output-options.sh $* | sort -u > $@
 
+.PHONY: clean
 clean:
 	rm -f commands*.txt generic-options.txt options-*.txt
 	rm -f hledger-completion.bash
diff --git a/shell-completion/README.md b/shell-completion/README.md
index 8c9d961ab..9804b608c 100644
--- a/shell-completion/README.md
+++ b/shell-completion/README.md
@@ -69,8 +69,10 @@ cd shell-completion/
 make
 ```
 
-Hint: GNU make, GNU m4, and GNU parallel must be installed to call `make`.
-The first two usually are.
+Hint: GNU make and  GNU m4 must be installed to call `make`.
+These are present on most systems anyway.
+Additionally the build will run a lot faster with parallell jobs.
+Use `make -j$(nproc)` for best effect.
 
 The generated completion script must be installed. The package maintainer for
 your distribution should be responsible for this.