diff --git a/src/sqlite4clj/core.clj b/src/sqlite4clj/core.clj
index c245a85..c8460c9 100644
--- a/src/sqlite4clj/core.clj
+++ b/src/sqlite4clj/core.clj
@@ -224,6 +224,32 @@
            :pragma    (merge pragma writer-pragma)
            :vfs       vfs
            :default-result-set-fn default-result-set-fn})
+        ;; Defensive: force -wal/-shm files to materialize before opening
+        ;; the read-only reader pool.  On a fresh WAL database the writer
+        ;; pool sets journal_mode=WAL but no -shm/-wal files exist yet
+        ;; (no write has happened).  Per SQLite WAL docs §5, a
+        ;; SQLITE_OPEN_READONLY connection can attach to a WAL DB only if
+        ;; -shm/-wal already exist or the database is opened immutable.
+        ;; macOS's stock sqlite3 3.51.0 demonstrates this deterministically:
+        ;;
+        ;;   $ sqlite3 fresh.db "PRAGMA journal_mode=WAL;"
+        ;;   $ sqlite3 -readonly fresh.db "PRAGMA cache_size=15625;"
+        ;;   Error: in prepare, unable to open database file (14)
+        ;;
+        ;; The bundled SQLite 3.51.3 in this library is more permissive in
+        ;; isolated tests, but the failure has been observed in production
+        ;; on macOS — likely a timing/VFS interaction that does not
+        ;; reliably reproduce in a fresh JVM.  A no-op write tx here is
+        ;; the cheapest way to satisfy the docs' condition (1) regardless
+        ;; of which SQLite/OS quirks are in play.
+        _ (when-not (= ":memory:" url)
+            (let [conn-pool (:conn-pool writer)
+                  conn      (BlockingQueue/.take conn-pool)]
+              (try
+                (q* conn ["BEGIN IMMEDIATE"] default-result-set-fn)
+                (q* conn ["COMMIT"] default-result-set-fn)
+                (finally
+                  (BlockingQueue/.offer conn-pool conn)))))
         ;; Pool of read connections
         reader (if (= ":memory:" url)
                  writer
diff --git a/test/sqlite4clj/core_test.clj b/test/sqlite4clj/core_test.clj
index 4b96561..317fba4 100644
--- a/test/sqlite4clj/core_test.clj
+++ b/test/sqlite4clj/core_test.clj
@@ -124,3 +124,23 @@
                                ["select length(data) from raw_bytes where id = 1"])]
           (is (= (seq payload) (seq stored-bytes)))
           (is (= (inc (alength payload)) stored-length)))))))
+
+(deftest init-db-on-fresh-wal-database
+  (testing "init-db! works on a brand-new file with default WAL pragmas.
+
+  This is a smoke test, not a strict regression test: the fresh-WAL failure
+  this change defends against (see the comment in init-db!) does not
+  reliably reproduce against the bundled SQLite in a fresh JVM, even though
+  it has been observed in production on macOS and is reproducible at the
+  SQLite CLI level (3.51.0).  This test just verifies that the warmup tx
+  doesn't break the normal happy path."
+    (let [path "test-data/fresh-wal.db"]
+      (clojure.java.io/delete-file (clojure.java.io/file path) true)
+      (clojure.java.io/delete-file (clojure.java.io/file (str path "-shm")) true)
+      (clojure.java.io/delete-file (clojure.java.io/file (str path "-wal")) true)
+      (with-db [db (d/init-db! path {:pool-size 2})]
+        (is (some? (:writer db)))
+        (is (some? (:reader db)))
+        (d/q (:writer db) ["CREATE TABLE t (x INT)"])
+        (d/q (:writer db) ["INSERT INTO t VALUES (1)"])
+        (is (= [1] (d/q (:reader db) ["SELECT x FROM t"])))))))