diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 6686c7a4cf3..49748f39aba 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -160,6 +160,10 @@ jobs:
 
       - name: Install Foundry
         uses: foundry-rs/foundry-toolchain@v1
+        with:
+          # Pinned to specific version since newer versions do not produce
+          # deterministic block hashes. Unpin once that's fixed upstream
+          version: v1.2.3
       - name: Start anvil
         run: anvil --gas-limit 100000000000 --base-fee 1 --block-time 2 --timestamp 1743944919 --port 3021 &
 
diff --git a/tests/docker-compose.yml b/tests/docker-compose.yml
index 7385b4b08a2..19dfa1f86c5 100644
--- a/tests/docker-compose.yml
+++ b/tests/docker-compose.yml
@@ -20,7 +20,9 @@ services:
       POSTGRES_DB: graph-node
       POSTGRES_INITDB_ARGS: "-E UTF8 --locale=C"
   anvil:
-    image: ghcr.io/foundry-rs/foundry:stable
+    # Pinned to specific version since newer versions do not produce
+    # deterministic block hashes. Unpin once that's fixed upstream
+    image: ghcr.io/foundry-rs/foundry:v1.2.3
     ports:
       - '3021:8545'
     command: "'anvil --host 0.0.0.0 --gas-limit 100000000000 --base-fee 1 --block-time 2 --timestamp 1743944919 --mnemonic \"test test test test test test test test test test test junk\"'"