diff --git a/hosts/vaulttest01/configuration.nix b/hosts/vaulttest01/configuration.nix
index 76342ff..96baf1e 100644
--- a/hosts/vaulttest01/configuration.nix
+++ b/hosts/vaulttest01/configuration.nix
@@ -105,6 +105,17 @@
     };
   };
 
+  # Test ACME certificate issuance from OpenBao PKI
+  # Override the global ACME server (from system/acme.nix) to use OpenBao instead of step-ca
+  security.acme.defaults.server = lib.mkForce "https://vault01.home.2rjus.net:8200/v1/pki_int/acme/directory";
+
+  # Request a certificate for this host
+  # Using HTTP-01 challenge with standalone listener on port 80
+  security.acme.certs."vaulttest01.home.2rjus.net" = {
+    listenHTTP = ":80";
+    enableDebugLogs = true;
+  };
+
   system.stateVersion = "25.11"; # Did you read the comment?
 }
 
diff --git a/services/vault/default.nix b/services/vault/default.nix
index bb30d60..3439a67 100644
--- a/services/vault/default.nix
+++ b/services/vault/default.nix
@@ -77,8 +77,89 @@ let
       fi
     '';
   };
+
+  bootstrapCertScript = pkgs.writeShellApplication {
+    name = "bootstrap-vault-cert";
+    runtimeInputs = with pkgs; [
+      openbao
+      jq
+      openssl
+      coreutils
+    ];
+    text = ''
+      # Bootstrap vault01 with a proper certificate from its own PKI
+      # This solves the chicken-and-egg problem where ACME clients can't trust
+      # vault01's self-signed certificate.
+
+      echo "=== Bootstrapping vault01 certificate ==="
+
+      # Use Unix socket to avoid TLS issues
+      export BAO_ADDR='unix:///run/openbao/openbao.sock'
+
+      # ACME certificate directory
+      CERT_DIR="/var/lib/acme/vault01.home.2rjus.net"
+
+      # Issue certificate for vault01 with vault as SAN
+      echo "Issuing certificate for vault01.home.2rjus.net (with SAN: vault.home.2rjus.net)..."
+      OUTPUT=$(bao write -format=json pki_int/issue/homelab \
+        common_name="vault01.home.2rjus.net" \
+        alt_names="vault.home.2rjus.net" \
+        ttl="720h")
+
+      # Create ACME directory structure
+      echo "Creating ACME certificate directory..."
+      mkdir -p "$CERT_DIR"
+
+      # Extract certificate components to temp files
+      echo "$OUTPUT" | jq -r '.data.certificate' > /tmp/vault01-cert.pem
+      echo "$OUTPUT" | jq -r '.data.private_key' > /tmp/vault01-key.pem
+      echo "$OUTPUT" | jq -r '.data.issuing_ca' > /tmp/vault01-ca.pem
+
+      # Create fullchain (cert + CA)
+      cat /tmp/vault01-cert.pem /tmp/vault01-ca.pem > /tmp/vault01-fullchain.pem
+
+      # Backup old certificates if they exist
+      if [ -f "$CERT_DIR/fullchain.pem" ]; then
+        echo "Backing up old certificate..."
+        cp "$CERT_DIR/fullchain.pem" "$CERT_DIR/fullchain.pem.backup"
+        cp "$CERT_DIR/key.pem" "$CERT_DIR/key.pem.backup"
+      fi
+
+      # Install new certificates
+      echo "Installing new certificate..."
+      mv /tmp/vault01-fullchain.pem "$CERT_DIR/fullchain.pem"
+      mv /tmp/vault01-cert.pem "$CERT_DIR/cert.pem"
+      mv /tmp/vault01-ca.pem "$CERT_DIR/chain.pem"
+      mv /tmp/vault01-key.pem "$CERT_DIR/key.pem"
+
+      # Set proper ownership and permissions (ACME-style)
+      chown -R acme:acme "$CERT_DIR"
+      chmod 750 "$CERT_DIR"
+      chmod 640 "$CERT_DIR"/*.pem
+
+      echo "Certificate installed successfully!"
+      echo ""
+      echo "Certificate details:"
+      openssl x509 -in "$CERT_DIR/cert.pem" -noout -subject -issuer -dates
+      echo ""
+      echo "Subject Alternative Names:"
+      openssl x509 -in "$CERT_DIR/cert.pem" -noout -ext subjectAltName
+
+      echo ""
+      echo "Now restart openbao service:"
+      echo "  systemctl restart openbao"
+      echo ""
+      echo "After restart, verify ACME endpoint is accessible:"
+      echo "  curl https://vault01.home.2rjus.net:8200/v1/pki_int/acme/directory"
+      echo ""
+      echo "Once working, ACME will automatically manage certificate renewals."
+    '';
+  };
 in
 {
+  # Make bootstrap script available as a command
+  environment.systemPackages = [ bootstrapCertScript ];
+
   services.openbao = {
     enable = true;
 
@@ -101,8 +182,8 @@ in
 
   systemd.services.openbao.serviceConfig = {
     LoadCredential = [
-      "key.pem:/var/lib/openbao/key.pem"
-      "cert.pem:/var/lib/openbao/cert.pem"
+      "key.pem:/var/lib/acme/vault01.home.2rjus.net/key.pem"
+      "cert.pem:/var/lib/acme/vault01.home.2rjus.net/fullchain.pem"
     ];
     # TPM2-encrypted unseal key (created manually, see setup instructions)
     LoadCredentialEncrypted = [
@@ -110,5 +191,16 @@ in
     ];
     # Auto-unseal on service start
     ExecStartPost = "${unsealScript}/bin/openbao-unseal";
+    # Add openbao user to acme group to read certificates
+    SupplementaryGroups = [ "acme" ];
+  };
+
+  # ACME certificate management
+  # Bootstrapped with bootstrap-vault-cert, now managed by ACME
+  security.acme.certs."vault01.home.2rjus.net" = {
+    server = "https://vault01.home.2rjus.net:8200/v1/pki_int/acme/directory";
+    listenHTTP = ":80";
+    reloadServices = [ "openbao" ];
+    extraDomainNames = [ "vault.home.2rjus.net" ];
   };
 }
diff --git a/system/default.nix b/system/default.nix
index 7957c30..3c59c8c 100644
--- a/system/default.nix
+++ b/system/default.nix
@@ -7,7 +7,7 @@
     ./packages.nix
     ./nix.nix
     ./root-user.nix
-    ./root-ca.nix
+    ./pki/root-ca.nix
     ./sops.nix
     ./sshd.nix
     ./vault-secrets.nix
diff --git a/system/root-ca.crt b/system/pki/root-ca.crt
similarity index 100%
rename from system/root-ca.crt
rename to system/pki/root-ca.crt
diff --git a/system/root-ca.nix b/system/pki/root-ca.nix
similarity index 84%
rename from system/root-ca.nix
rename to system/pki/root-ca.nix
index 5e5ff78..0397351 100644
--- a/system/root-ca.nix
+++ b/system/pki/root-ca.nix
@@ -4,6 +4,7 @@
     certificateFiles = [
       "${pkgs.cacert}/etc/ssl/certs/ca-bundle.crt"
       ./root-ca.crt
+      ./vault-root-ca.crt
     ];
   };
 }
diff --git a/system/pki/vault-root-ca.crt b/system/pki/vault-root-ca.crt
new file mode 100644
index 0000000..c45d391
--- /dev/null
+++ b/system/pki/vault-root-ca.crt
@@ -0,0 +1,14 @@
+-----BEGIN CERTIFICATE-----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+-----END CERTIFICATE-----
\ No newline at end of file
diff --git a/terraform/vault/pki.tf b/terraform/vault/pki.tf
index 7583d41..23d47c8 100644
--- a/terraform/vault/pki.tf
+++ b/terraform/vault/pki.tf
@@ -62,6 +62,13 @@ resource "vault_mount" "pki_int" {
   description               = "Intermediate CA"
   default_lease_ttl_seconds = 157680000 # 5 years
   max_lease_ttl_seconds     = 157680000 # 5 years
+
+  # Required for ACME support - allow ACME-specific response headers
+  allowed_response_headers = [
+    "Replay-Nonce",
+    "Link",
+    "Location"
+  ]
 }
 
 resource "vault_pki_secret_backend_intermediate_cert_request" "intermediate" {
@@ -139,6 +146,33 @@ resource "vault_pki_secret_backend_config_urls" "config_urls" {
   ]
 }
 
+# Configure cluster path (required for ACME)
+resource "vault_pki_secret_backend_config_cluster" "cluster" {
+  backend  = vault_mount.pki_int.path
+  path     = "${var.vault_address}/v1/${vault_mount.pki_int.path}"
+  aia_path = "${var.vault_address}/v1/${vault_mount.pki_int.path}"
+}
+
+# Enable ACME support
+resource "vault_generic_endpoint" "acme_config" {
+  depends_on = [
+    vault_pki_secret_backend_config_cluster.cluster,
+    vault_pki_secret_backend_role.homelab
+  ]
+
+  path                 = "${vault_mount.pki_int.path}/config/acme"
+  ignore_absent_fields = true
+  disable_read         = true
+  disable_delete       = true
+
+  data_json = jsonencode({
+    enabled                  = true
+    allowed_issuers          = ["*"]
+    allowed_roles            = ["*"]
+    default_directory_policy = "sign-verbatim"
+  })
+}
+
 # ============================================================================
 # Direct Certificate Issuance (Non-ACME)
 # ============================================================================
diff --git a/terraform/vms.tf b/terraform/vms.tf
index cf15eef..de8e2af 100644
--- a/terraform/vms.tf
+++ b/terraform/vms.tf
@@ -50,8 +50,8 @@ locals {
       cpu_cores           = 2
       memory              = 2048
       disk_size           = "20G"
-      flake_branch        = "vault-bootstrap-integration"
-      vault_wrapped_token = "s.HwNenAYvXBsPs8uICh4CbE11"
+      flake_branch        = "pki-migration"
+      vault_wrapped_token = "s.UCpQCOp7cOKDdtGGBvfRWwAt"
     }
   }