diff --git a/rbf/db_test.go b/rbf/db_test.go
index 039d907f3..d637860e0 100644
--- a/rbf/db_test.go
+++ b/rbf/db_test.go
@@ -39,6 +39,25 @@ func TestDB_Open(t *testing.T) {
 	}
 }
 
+func TestDB_WAL(t *testing.T) {
+	t.Run("ErrTxTooLarge", func(t *testing.T) {
+		config := rbfcfg.NewDefaultConfig()
+		config.MaxWALSize = 4 * rbf.PageSize
+
+		db := MustOpenDB(t, config)
+		defer MustCloseDB(t, db)
+
+		tx := MustBegin(t, db, true)
+		defer tx.Rollback()
+
+		if err := tx.CreateBitmap("x"); err != nil {
+			t.Fatal(err)
+		} else if err := tx.CreateBitmap("y"); err != rbf.ErrTxTooLarge {
+			t.Fatalf("unexpected error: %v", err)
+		}
+	})
+}
+
 func TestDB_Recovery(t *testing.T) {
 	// Ensure a bitmap header written without a bitmap is truncated.
 	t.Run("TruncPartialWALBitmap", func(t *testing.T) {
diff --git a/rbf/rbf.go b/rbf/rbf.go
index 4dd8d6b43..e3a293a26 100644
--- a/rbf/rbf.go
+++ b/rbf/rbf.go
@@ -105,6 +105,7 @@ var (
 	ErrBitmapNameRequired = errors.New("bitmap name required")
 	ErrBitmapNotFound     = errors.New("bitmap not found")
 	ErrBitmapExists       = errors.New("bitmap already exists")
+	ErrTxTooLarge         = errors.New("rbf tx too large")
 )
 
 // Debug is just a temporary flag used for debugging.
diff --git a/rbf/tx.go b/rbf/tx.go
index 6c822f18c..72d041704 100644
--- a/rbf/tx.go
+++ b/rbf/tx.go
@@ -69,7 +69,12 @@ func (tx *Tx) Writable() bool {
 
 // dirty returns true if any pages have been updated in this tx.
 func (tx *Tx) dirty() bool {
-	return len(tx.dirtyPages) != 0 || len(tx.dirtyBitmapPages) != 0
+	return tx.dirtyN() != 0
+}
+
+// dirtyN returns the number of dirty pages.
+func (tx *Tx) dirtyN() int {
+	return len(tx.dirtyPages) + len(tx.dirtyBitmapPages)
 }
 
 // PageN returns the number of pages in the database as seen by this transaction.
@@ -954,11 +959,18 @@ func (tx *Tx) readPage(pgno uint32) ([]byte, error) {
 
 func (tx *Tx) writePage(page []byte) error {
 	tx.dirtyPages[readPageNo(page)] = page
-	return nil
+	return tx.checkTxSize()
 }
 
 func (tx *Tx) writeBitmapPage(pgno uint32, page []byte) error {
 	tx.dirtyBitmapPages[pgno] = page
+	return tx.checkTxSize()
+}
+
+func (tx *Tx) checkTxSize() error {
+	if (tx.walPageN+tx.dirtyN())*PageSize >= len(tx.db.wal) {
+		return ErrTxTooLarge
+	}
 	return nil
 }