diff --git a/.github/workflows/build.yml b/.github/workflows/build.yml
index 31a94891..b1bfb084 100644
--- a/.github/workflows/build.yml
+++ b/.github/workflows/build.yml
@@ -5,6 +5,10 @@ on:
     branches: ['**']
   pull_request:
 
+permissions:
+  contents: read
+  pull-requests: write
+
 jobs:
   build:
     runs-on: ubuntu-latest
@@ -13,18 +17,48 @@ jobs:
 
     steps:
       - uses: actions/checkout@v6
+        with:
+          path: branch
+
+      - uses: actions/checkout@v6
+        with:
+          path: main
+          ref: main
 
       - name: Install dependencies
         run: |
           apt update
           apt install make gcc sdcc xxd python-is-python3 libjson-c-dev zlib1g-dev -y
       - name: Run the host-side unit tests
-        run: make -C test
+        run: cd branch && make -C test
       - name: Check that every machine definition can be compiled
-        run: make machine_check
+        run: cd branch && make machine_check
       - name: Make project (4x2/RTL8372)
-        run: make CI=1 MACHINE="KP_9000_6XHML_X2"
+        run: cd branch && make CI=1 MACHINE="KP_9000_6XHML_X2" && cp output/KP_9000_6XHML_X2/rtlplayground.map /tmp/branch.map
       - name: Make project (8x1/RTL8373)
-        run: make CI=1 MACHINE="KP_9000_9XHML_X_V3_1"
+        run: cd branch && make CI=1 MACHINE="KP_9000_9XHML_X_V3_1"
       - name: Make project with the health instrumentation
-        run: make clean && make CI=1 MACHINE="KP_9000_6XHML_X2" HEALTH=1
+        run: cd branch && make clean && make CI=1 MACHINE="KP_9000_6XHML_X2" HEALTH=1
+      - name: Make main
+        run: cd main && make CI=1 MACHINE="KP_9000_6XHML_X2" && cp output/KP_9000_6XHML_X2/rtlplayground.map /tmp/main.map
+      - name: Calculate bank growth
+        run: |
+          sed -rn 's/^([XCD]SEG|(BANK[0-9])).*=\s+([0-9]+)\. bytes.*$/MAIN_\1=\3/p' /tmp/main.map | sort | uniq >> "$GITHUB_ENV"
+          sed -rn 's/^([XCD]SEG|(BANK[0-9])).*=\s+([0-9]+)\. bytes.*$/BRANCH_\1=\3/p' /tmp/branch.map | sort | uniq >> "$GITHUB_ENV"
+      - name: Update PR comment
+        uses: marocchino/sticky-pull-request-comment@v2
+        with:
+          header: Sizes
+          message: |
+            ## Image Growth
+
+            Commit: ${{ github.sha }}
+
+            | Bank # | Main | Branch |
+            | --- | --- | --- |
+            | XSEG | ${{ env.MAIN_XSEG }} bytes | ${{ env.BRANCH_XSEG }} bytes |
+            | CSEG | ${{ env.MAIN_CSEG }} bytes | ${{ env.BRANCH_CSEG }} bytes |
+            | DSEG | ${{ env.MAIN_DSEG }} bytes | ${{ env.BRANCH_DSEG }} bytes |
+            | 1 | ${{ env.MAIN_BANK1 }} bytes | ${{ env.BRANCH_BANK1 }} bytes |
+            | 2 | ${{ env.MAIN_BANK2 }} bytes | ${{ env.BRANCH_BANK2 }} bytes |
+            | 3 | ${{ env.MAIN_BANK3 }} bytes | ${{ env.BRANCH_BANK3 }} bytes |