diff --git a/.devcontainer/devcontainer.json b/.devcontainer/devcontainer.json
index b845dee..5cf3826 100644
--- a/.devcontainer/devcontainer.json
+++ b/.devcontainer/devcontainer.json
@@ -15,7 +15,7 @@
       ]
     }
   },
-  "initializeCommand": "docker pull gvenzl/oracle-free:latest",
+  "initializeCommand": "bash .devcontainer/initializeCommand.sh",
   "postCreateCommand": "bash .devcontainer/postCreateCommand.sh",
   "remoteEnv": {
     "DATABASE_NAME": "FREEPDB1",
diff --git a/.devcontainer/docker-compose.yml b/.devcontainer/docker-compose.yml
index ae47d9a..4e2c380 100644
--- a/.devcontainer/docker-compose.yml
+++ b/.devcontainer/docker-compose.yml
@@ -5,6 +5,7 @@ services:
       dockerfile: Dockerfile
     volumes:
       - ../..:/workspaces:cached
+      - ./tzdata:/opt/tzdata:ro
     command: sleep infinity
     network_mode: service:oracle
 
diff --git a/.devcontainer/initializeCommand.sh b/.devcontainer/initializeCommand.sh
new file mode 100755
index 0000000..6159e08
--- /dev/null
+++ b/.devcontainer/initializeCommand.sh
@@ -0,0 +1,19 @@
+#!/usr/bin/env bash
+
+set -euo pipefail
+
+IMAGE=gvenzl/oracle-free:latest
+SCRIPT_DIR=$(cd "$(dirname "$0")" && pwd)
+OUT_DIR="$SCRIPT_DIR/tzdata"
+
+docker pull "$IMAGE"
+
+mkdir -p "$OUT_DIR"
+rm -f "$OUT_DIR"/timezlrg_*.dat "$OUT_DIR"/timezdif_*.dat
+
+docker run --rm --entrypoint sh \
+  -v "$OUT_DIR:/out" \
+  "$IMAGE" \
+  -c 'cp "$ORACLE_HOME"/oracore/zoneinfo/timezlrg_*.dat /out/ && chmod a+r /out/*.dat'
+
+ls -1 "$OUT_DIR"
diff --git a/.devcontainer/postCreateCommand.sh b/.devcontainer/postCreateCommand.sh
index 22c8c4b..35e6581 100755
--- a/.devcontainer/postCreateCommand.sh
+++ b/.devcontainer/postCreateCommand.sh
@@ -5,6 +5,18 @@ set -e
 gem update --system
 bundle install
 
+# Match Instant Client TZ data to the Oracle server's to avoid ORA-01805.
+# The file is extracted from the gvenzl image into .devcontainer/tzdata/ by
+# initializeCommand.sh and bind-mounted read-only at /opt/tzdata.
+TZ_FILE=$(ls /opt/tzdata/timezlrg_*.dat 2>/dev/null | head -1)
+if [ -n "$TZ_FILE" ]; then
+  echo "Using $TZ_FILE for Instant Client TZ data."
+  export ORA_TZFILE="$TZ_FILE"
+  echo "export ORA_TZFILE=$TZ_FILE" | sudo tee /etc/profile.d/ora-tzfile.sh > /dev/null
+else
+  echo "Warning: no timezlrg_*.dat found under /opt/tzdata; skipping ORA_TZFILE setup." >&2
+fi
+
 echo "Waiting for Oracle to be ready..."
 oracle_ready=false
 for i in $(seq 1 30); do
diff --git a/.gitignore b/.gitignore
index 8aeed57..e5808ef 100644
--- a/.gitignore
+++ b/.gitignore
@@ -13,3 +13,4 @@ Gemfile.lock
 *.zip
 .idea
 spec/support/custom_config.rb
+.devcontainer/tzdata/