diff --git a/README.md b/README.md
index 5d63d6857..0e55b7808 100644
--- a/README.md
+++ b/README.md
@@ -232,11 +232,9 @@ In principle you can change other things too, but this is generally frowned upon
 
 This repository contains a convenience script for adding a revision to CHaP:
 ```
-$ ./scripts/add-revision.sh _repo PACKAGE_NAME PACKAGE_VERSION
+$ ./scripts/add-revision.sh PACKAGE_NAME PACKAGE_VERSION
 ```
 
-`_repo` needs to point to a [built package repository](#how-to-get-the-built-cabal-package-repository).
-It will add a new revision and copy the _current_ cabal file in as the revised cabal file.
 You can then edit that file and commit the result.
 
 ### How to add a patched versions of a Hackage package 
diff --git a/scripts/add-revision.sh b/scripts/add-revision.sh
index 1dcdbfdec..4393372a3 100755
--- a/scripts/add-revision.sh
+++ b/scripts/add-revision.sh
@@ -5,7 +5,7 @@ set -o pipefail
 SCRIPT_DIR=$(dirname "$(which "$0")")
 
 function usage {
-  echo "Usage $(basename "$0") BUILT_REPO PKG_NAME PKG_VERSION"
+  echo "Usage $(basename "$0") PKG_NAME PKG_VERSION"
   echo "  Adds a new revision with the existing cabal file for that package"
   echo "  version. Requires a built repository. Does not commit."
   exit
@@ -28,15 +28,18 @@ done
 
 shift $((OPTIND - 1))
 
-BUILT_REPO=$1
-PKG_NAME=$2
-PKG_VERSION=$3
+PKG_NAME=$1
+PKG_VERSION=$2
 
-if ! shift 3; then
+if ! shift 2; then
   usage
   exit 1
 fi
 
+BUILT_REPO=$(mktemp -d)
+mkdir -p $BUILT_REPO/index
+curl -L https://input-output-hk.github.io/cardano-haskell-packages/01-index.tar.gz | tar -C $BUILT_REPO/index -xz
+
 META_DIR="_sources/$PKG_NAME/$PKG_VERSION"
 META_FILE="$META_DIR/meta.toml"
 REVISIONS_DIR="$META_DIR/revisions"
@@ -63,10 +66,11 @@ else
   LATEST_REVISION=$(echo "$CURRENT_REVISIONS" | sort | tail -n1)
   LATEST_REVISION_NUMBER=$(basename "$LATEST_REVISION" | cut -f 1 -d '.')
   NEW_REVISION_NUMBER=$((LATEST_REVISION_NUMBER+1))
+  CURRENT_CABAL_FILE="$REVISIONS_DIR/$LATEST_REVISION_NUMBER.cabal"
 fi
 
 NEW_CABAL_FILE="$REVISIONS_DIR/$NEW_REVISION_NUMBER.cabal"
-echo "Moving $CURRENT_CABAL_FILE to $NEW_CABAL_FILE"
+echo "Copying $CURRENT_CABAL_FILE to $NEW_CABAL_FILE"
 
 mkdir -p "$REVISIONS_DIR"
 cp "$CURRENT_CABAL_FILE" "$NEW_CABAL_FILE"
diff --git a/scripts/current-timestamp.sh b/scripts/current-timestamp.sh
index a6325b2ea..1a08909f5 100755
--- a/scripts/current-timestamp.sh
+++ b/scripts/current-timestamp.sh
@@ -1,8 +1,3 @@
 #!/usr/bin/env bash
 
-# Use gnu-tar and gnu-date regardless of whether the OS is Linux
-# or BSD-based.  The correct command will be assigned to TAR and DATE
-# variables.
-source "$(dirname "$(which "$0")")/use-gnu-tar.sh"
-
-"$DATE" --utc +%Y-%m-%dT%H:%M:%SZ
+date -u +%Y-%m-%dT%H:%M:%SZ
diff --git a/scripts/use-gnu-tar.sh b/scripts/use-gnu-tar.sh
index 3d769e7ce..fe4161eee 100755
--- a/scripts/use-gnu-tar.sh
+++ b/scripts/use-gnu-tar.sh
@@ -1,12 +1,8 @@
 #!/usr/bin/env bash
 
-export DATE="date"
 export TAR="tar"
 
 if [[ "$(uname -s)" == "Darwin" ]]; then
-  if [[ "$(which date)" == "/bin/date" ]]; then
-    export DATE="gdate"
-  fi
   if [[ "$(which tar)" == "/usr/bin/tar" ]]; then
     export TAR="gtar"
   fi