diff --git a/bin/commitlint b/bin/commitlint
index b32899c82..1b144ea49 100755
--- a/bin/commitlint
+++ b/bin/commitlint
@@ -1,21 +1,23 @@
 #!/usr/bin/env bash
-# shellcheck disable=SC2059
 #
-# Check git commits for compliance with hledger's conventions,
-# described at https://hledger.org/CONTRIBUTING.html#commit-messages.
-#
-# Usage:
-# commitlint [GITREV|GITRANGE]
-#   Checks unpushed commits, or the specified commit or range.
-#   If the argument contains - or .. it's a range, otherwise a single commit.
+# commitlint [GITRANGE|FILE]
+
+# Check unpushed commits, or commits in the specified range, or a
+# commit message in FILE, for compliance with hledger's conventions
+# (https://hledger.org/CONTRIBUTING.html#commit-messages). If the
+# argument contains - or .. or ^! it's a range, otherwise a file
+# containing a proposed commit message. 
+# Run interactively, or symlink as .git/hooks/commit-msg to check
+# your messages before commit.
 #
 # Examples:
-# commitlint                              # unpushed commits
-# commitlint HEAD                         # last commit
-# commitlint d5d19f841                    # this commit
+# commitlint foo                          # commit message in ./foo
+# commitlint HEAD^!                       # last commit
+# commitlint d5d19f841^!                  # this commit
 # commitlint -20                          # last 20 commits
 # commitlint master..                     # commits in this branch
 # commitlint 1.21..1.22 | grep -F [FAIL]  # bad commits in 1.22 release cycle
+# commitlint                              # unpushed commits
 
 if [[ -n ${NO_COLOR+set} ]]
 then
@@ -32,39 +34,54 @@ fi
 function checkcommit()
 {
     HASH=${1}
-    SUMMARY=$(git log -1 "$HASH" --pretty=format:"%s")
+    MSG=$(git log -1 "$HASH" --pretty=format:"%s%n%b")
+    checkmsg "$MSG"
+}
+
+# checkmsg MSG [GITHASH] - check this commit message and print result
+function checkmsg()
+{
+    MSG=${1}
+    HASH=${2}
+    if [[ -n $HASH ]]
+    then
+        HASH="$HASH "
+    fi
+
+    SUMMARY=$(echo "$MSG" | head -1)
+    FMT="%s%-60s  %b${NRM}\n"
 
     # Does the summary have a type: prefix ?
     # Can begin with ; and/or end with !, some spaces are tolerated.
-    FMT="%s %-60s  %b${NRM}\n"
     if ! echo "$SUMMARY" | grep -qE '^(; *)?\w+:[ \w]+!?'
     then
+        # shellcheck disable=SC2059
         printf "$FMT" "$HASH" "$SUMMARY" "${RED}[FAIL]"
         STATUS=1
     else
+        # shellcheck disable=SC2059
         printf "$FMT" "$HASH" "$SUMMARY" "${GRN}[ok]"
     fi
 }
 
+STATUS=
 RANGE=${*:-"@{u}.."}  # @{u} = upstream
 
-if [[ ! $RANGE =~ (-|\.\.) ]]
+if [[ $RANGE =~ (-|\.\.|\^!) ]]
 then
-    RANGE=$RANGE^!  # assume range is a single commit
+    HASHES=$(git log --abbrev-commit --pretty=format:%h "$RANGE")
+    for HASH in $HASHES; do checkcommit "$HASH"; done
+else
+    MSG=$(cat "$1")
+    checkmsg "$MSG"
 fi
 
-HASHES=$(git log --abbrev-commit --pretty=format:%h "$RANGE")
-
-STATUS=
-for HASH in $HASHES; do
-    checkcommit "$HASH"
-done
-
 if [[ -z $STATUS ]]
 then
     printf "" # "${GRN}Ok${NRM}\n"
 else
-    printf "\n${RED}Some commits are not in preferred style.${NRM}\n"
+    # shellcheck disable=SC2059
+    printf "\n${RED}Commit(s) not in preferred style.${NRM}\n"
     cat <<EOF
 ---------------------------------------------------------------------------
 Commit messages should follow this format:
@@ -80,15 +97,16 @@ The subject line should have a type: prefix. Common types:
  cha pkg lib             - packager/builder/lib-user changes (->changelogs)
  dev doc test ci ref cln - developer changes
 
-It may additionally have a topic prefix such as:
+It may additionally have a topic(s) prefix such as:
+ bin examples install cli ui web print reg bal bs balcmds journal csv ...
  (see https://hledger.org/CONTRIBUTING.html#open-issues -> COMPONENT)
 
 Mention any related issues, usually parenthesised at end of summary: (#1234)
 ! indicates a breaking change.
 ; skips expensive CI tests.
 
-These conventions are evolving. In practice, any type or topic will
-do. Use your best judgement and we'll polish during code review.
+These conventions are evolving. In practice, any type or topic will do.
+Use your best judgement and we'll polish during code review.
 More detail: https://hledger.org/CONTRIBUTING.html#commit-messages
 ---------------------------------------------------------------------------
 EOF