diff --git a/tests/test_version-lookup.bats b/tests/test_version-lookup.bats
index 1287999..b0864e8 100644
--- a/tests/test_version-lookup.bats
+++ b/tests/test_version-lookup.bats
@@ -110,18 +110,6 @@ function init_repo {
     [[ "$output" = *"CURRENT_VERSION=$(date '+%Y.%-m.0')"* ]]
 }
 
-@test "converts from older calver scheme automatically" {
-    init_repo
-
-    git tag 2020-09-R2
-
-    run ../../version-lookup.sh
-
-    print_run_info
-    [ "$status" -eq 0 ] &&
-    [[ "$output" = *"CURRENT_VERSION=2020.9.2"* ]]
-}
-
 @test "strips v from the version" {
     init_repo
 
diff --git a/version-lookup.sh b/version-lookup.sh
index 58c3fae..130ca89 100755
--- a/version-lookup.sh
+++ b/version-lookup.sh
@@ -10,18 +10,6 @@ if [[ "${input_errors}" == 'true' ]] ; then
     exit 8
 fi
 
-##==----------------------------------------------------------------------------
-##  MacOS compatibility - for local testing
-
-export grep="grep"
-if [[ "$(uname)" == "Darwin" ]] ; then
-    export grep="ggrep"
-    if ! grep --version 1>/dev/null ; then
-        echo "🛑 GNU grep not installed, try brew install coreutils" 1>&2
-        exit 9
-    fi
-fi
-
 ##==----------------------------------------------------------------------------
 ##  Get tags from GitHub repo
 
@@ -53,15 +41,6 @@ else
     )"
 fi
 
-# support transition from an old reecetech calver style (yyyy-mm-Rr, where R is the literal `R`, and r is the nth release for the month)
-if [[ -z "${current_version:-}" ]] ; then
-    current_version="$(git tag -l | { ${grep} -P "${pcre_old_calver}" || true; } | sort -V | tail -n 1)"
-    if [[ -n "${current_version:-}" ]] ; then
-        # convert - to . and drop leading zeros & the R
-        current_version="$(echo "${current_version}" | sed -r 's/^([0-9]+)-0{0,1}([0-9]+)-R0{0,1}([0-9]+)$/\1.\2.\3/')"
-    fi
-fi
-
 # handle no version detected - start versioning!
 if [[ -z "${current_version:-}" ]] ; then
     echo "⚠️ No previous release version identified in git tags"