diff --git a/data-raw/git_diff_main.sh b/data-raw/git_diff_main.sh
new file mode 100644
index 00000000..a088b4e0
--- /dev/null
+++ b/data-raw/git_diff_main.sh
@@ -0,0 +1,78 @@
+#!/bin/bash
+
+# A script to diff the current branch against the project's true main branch.
+# It handles both forked and non-forked repository scenarios robustly.
+# Its primary output (stdout) is the list of changed files.
+#
+# Usage: ./git_diff_main.sh <main_repo_url>
+
+set -e # Exit immediately if a command exits with a non-zero status.
+
+# --- Helper Function to Normalize Git URLs ---
+# This function reliably extracts the 'owner/repo' part from various URL formats.
+normalize_git_url() {
+  local url=$1
+  # Step 1: Remove an optional trailing slash
+  local repo_path=${url%/}
+  # Step 2: Remove the optional .git suffix
+  repo_path=${repo_path%.git}
+  # Step 3: Remove everything up to the last colon or slash
+  repo_path=${repo_path##*[:/]}
+
+  echo "$repo_path"
+}
+
+# --- 1. Validate Input ---
+UPSTREAM_URL="$1"
+if [ -z "$UPSTREAM_URL" ]; then
+  # Print usage instructions to standard error
+  echo "Usage: $0 <main_repo_url>" >&2
+  exit 1
+fi
+
+# --- 2. Determine Target and Fetch ---
+echo "Info: Analyzing repository remotes..." >&2
+TARGET_REMOTE=""
+ORIGIN_URL=$(git remote get-url origin 2>/dev/null || echo "") # Get origin URL or empty string
+
+# Normalize both URLs to get just the 'owner/repo' string for comparison.
+NORM_UPSTREAM_URL=$(normalize_git_url "$UPSTREAM_URL")
+NORM_ORIGIN_URL=$(normalize_git_url "$ORIGIN_URL")
+
+# Check if the normalized 'owner/repo' strings match
+if [[ -n "$NORM_ORIGIN_URL" && "$NORM_ORIGIN_URL" == "$NORM_UPSTREAM_URL" ]]; then
+  # Scenario: Running in the main (non-forked) repository.
+  echo "Info: Detected main repository." >&2
+  TARGET_REMOTE="origin"
+  echo "Info: Fetching latest data from 'origin' remote... (this may take a moment)" >&2
+  git fetch origin main --quiet
+else
+  # Scenario: Running in a fork or a repo with a mismatched origin URL.
+  echo "Info: Detected fork. Configuring 'upstream' remote." >&2
+  TARGET_REMOTE="upstream"
+  # Add or update the 'upstream' remote to point to the main repo
+  if ! git remote get-url "$TARGET_REMOTE" &>/dev/null; then
+    git remote add "$TARGET_REMOTE" "$UPSTREAM_URL"
+  else
+    git remote set-url "$TARGET_REMOTE" "$UPSTREAM_URL"
+  fi
+  echo "Info: Fetching latest data from 'upstream' remote... (this may take a moment)" >&2
+  git fetch "$TARGET_REMOTE" main --quiet
+fi
+
+TARGET_BRANCH="$TARGET_REMOTE/main"
+
+# --- 3. Safety Check: Avoid Diffing a Branch Against Itself ---
+CURRENT_TRACKING_BRANCH=$(git rev-parse --abbrev-ref '@{u}' 2>/dev/null || echo "")
+
+if [[ "$CURRENT_TRACKING_BRANCH" == "$TARGET_BRANCH" ]]; then
+  echo "Warning: Current branch is already tracking '$TARGET_BRANCH'. No changes to diff." >&2
+  # Exit successfully with no output
+  exit 0
+fi
+
+# --- 4. Final Output ---
+echo "Info: Comparing files against '$TARGET_BRANCH'..." >&2
+git diff "$TARGET_BRANCH" --name-only
+
+echo "Info: Done." >&2
diff --git a/data-raw/rebuild_cached_data.R b/data-raw/rebuild_cached_data.R
index 2d0d6fb5..9c71725b 100644
--- a/data-raw/rebuild_cached_data.R
+++ b/data-raw/rebuild_cached_data.R
@@ -46,10 +46,12 @@ flatten_list_of_deps <- function(updated_data, data_deps) {
   fin_up
 }
 
-
-library(random.cdisc.data)
-library(diffdf)
-library(dplyr)
+# Loading libs - not useful messaging is suppressed
+suppressMessages({
+  library(random.cdisc.data)
+  library(diffdf)
+  library(dplyr)
+})
 
 # Call function to match random number generation from previous R versions
 RNGkind(sample.kind = "Rounding")
@@ -76,7 +78,11 @@ data_deps <- sapply(
   }
 )
 
-git_call <- "git diff origin/main --name-only"
+if (!grepl(x = getwd(), pattern = "data-raw")) {
+  stop("This script should be run in the data-raw directory.")
+}
+
+git_call <- "bash ./git_diff_main.sh https://github.com/insightsengineering/random.cdisc.data/"
 updated_files <- tryCatch(
   system(git_call, intern = TRUE),
   error = function(e) e
diff --git a/vignettes/rebuild_cached_data.Rmd b/vignettes/rebuild_cached_data.Rmd
index d47e0081..1d270e14 100644
--- a/vignettes/rebuild_cached_data.Rmd
+++ b/vignettes/rebuild_cached_data.Rmd
@@ -29,5 +29,5 @@ datasets should be updated, edit the `data_to_update` vector below, entering the
 ## Update Cached Data
 
 **Note:** Prior to running the following code chunk, please ensure that you have reinstalled the `random.cdisc.data`
-package after completing all dataset modifications. Or use `devtools::load_all()` to reload functions. Execute the `data-raw/rebuild_cached_data.R` script to create, compare and save cached data to the `data/` directory.
+package after completing all dataset modifications. Or use `devtools::load_all()` to reload functions. Execute the `data-raw/rebuild_cached_data.R` script to create, compare and save cached data to the `data/` directory. We suggest to do `Rscript rebuild_cached_data.R` or `source("rebuild_cached_data.R")` from the `data-raw/` directory.