diff --git a/.github/scripts/de1-soc-synthesis-metrics-diff/aggregate_metrics.sh b/.github/scripts/de1-soc-synthesis-metrics-diff/aggregate_metrics.sh
index e395ada..599e4ca 100644
--- a/.github/scripts/de1-soc-synthesis-metrics-diff/aggregate_metrics.sh
+++ b/.github/scripts/de1-soc-synthesis-metrics-diff/aggregate_metrics.sh
@@ -6,6 +6,7 @@ set -euo pipefail
 
 ARTIFACTS_DIR="${1:-metrics-diff}"
 OUTPUT_FILE="${2:-comparison.md}"
+BASE_BRANCH="${BASE_BRANCH:-base branch}"
 
 append_metric_cell() {
   local file="$1"
@@ -43,4 +44,4 @@ fi
 
 echo "" >> "$OUTPUT_FILE"
 echo "---" >> "$OUTPUT_FILE"
-echo "*Comparing synthesis results from main branch vs. this PR*" >> "$OUTPUT_FILE"
+echo "*Comparing synthesis results from \`$BASE_BRANCH\` branch vs. this PR*" >> "$OUTPUT_FILE"
diff --git a/.github/scripts/de1-soc-synthesis-metrics-diff/compare_metrics_diff.sh b/.github/scripts/de1-soc-synthesis-metrics-diff/compare_metrics_diff.sh
index 9cbd9c1..9491884 100755
--- a/.github/scripts/de1-soc-synthesis-metrics-diff/compare_metrics_diff.sh
+++ b/.github/scripts/de1-soc-synthesis-metrics-diff/compare_metrics_diff.sh
@@ -1,17 +1,18 @@
 #!/bin/bash
-# Script to compare a synthesis report between main and PR branches
-# Usage: compare_metrics_diff.sh <main_report_path> <pr_report_path>
-# Example: compare_metrics_diff.sh "main-reports/report.summary" "pr-reports/report.summary"
+# Script to compare a synthesis report between base and PR branches
+# Usage: compare_metrics_diff.sh <base_report_path> <pr_report_path>
+# Example: compare_metrics_diff.sh "base-reports/report.summary" "pr-reports/report.summary"
 
 set -e
 
 if [ $# -lt 2 ]; then
-  echo "Usage: $0 <main_report_path> <pr_report_path>" >&2
+  echo "Usage: $0 <base_report_path> <pr_report_path>" >&2
   exit 1
 fi
 
-MAIN_REPORT="$1"
+BASE_REPORT="$1"
 PR_REPORT="$2"
+BASE_BRANCH="${BASE_BRANCH:-base branch}"
 
 if [ ! -f "$PR_REPORT" ]; then
   echo "ERROR: PR report not found at $PR_REPORT" >&2
@@ -19,9 +20,9 @@ if [ ! -f "$PR_REPORT" ]; then
 fi
 
 {
-  if [ -f "$MAIN_REPORT" ]; then
+  if [ -f "$BASE_REPORT" ]; then
     # Generate diff and capture output
-    DIFF_OUTPUT=$(diff -u "$MAIN_REPORT" "$PR_REPORT" | tail -n +3 || true)
+    DIFF_OUTPUT=$(diff -u "$BASE_REPORT" "$PR_REPORT" | tail -n +3 || true)
     if [ -z "$DIFF_OUTPUT" ]; then
       echo "*No changes detected*"
     else
@@ -30,7 +31,7 @@ fi
       echo "\`\`\`"
     fi
   else
-    echo "*No baseline available from main branch*"
+    echo "*No baseline available from \`$BASE_BRANCH\` branch*"
     echo ""
     echo "<details>"
     echo "<summary>View PR synthesis results</summary>"
diff --git a/.github/workflows/ci.yaml b/.github/workflows/ci.yaml
index 6a7fcc2..9fe0365 100644
--- a/.github/workflows/ci.yaml
+++ b/.github/workflows/ci.yaml
@@ -233,6 +233,8 @@ jobs:
     runs-on: ubuntu-latest
     permissions:
       pull-requests: write
+    env:
+      BASE_BRANCH: ${{ github.base_ref }}
 
     strategy:
       matrix: *utoss-risc-v-matrix
@@ -300,6 +302,8 @@ jobs:
     runs-on: ubuntu-latest
     permissions:
       pull-requests: write
+    env:
+      BASE_BRANCH: ${{ github.base_ref }}
 
     steps:
       - name: Checkout code