diff --git a/ext/lmdb_ext/lmdb_ext.c b/ext/lmdb_ext/lmdb_ext.c
index de26fd6..079c99b 100644
--- a/ext/lmdb_ext/lmdb_ext.c
+++ b/ext/lmdb_ext/lmdb_ext.c
@@ -206,6 +206,8 @@ static void stop_txn_begin(void *arg)
 
 static VALUE with_transaction(VALUE venv, VALUE(*fn)(VALUE), VALUE arg, int flags) {
         ENVIRONMENT(venv, environment);
+        if(environment->flags & MDB_RDONLY)
+          flags |= MDB_RDONLY;
 
         MDB_txn* txn;
         TxnArgs txn_args;
@@ -490,6 +492,7 @@ static VALUE environment_new(int argc, VALUE *argv, VALUE klass) {
         environment->env = env;
         environment->thread_txn_hash = rb_hash_new();
         environment->txn_thread_hash = rb_hash_new();
+        environment->flags = options.flags;
 
         if (options.maxreaders > 0)
                 check(mdb_env_set_maxreaders(env, options.maxreaders));
diff --git a/ext/lmdb_ext/lmdb_ext.h b/ext/lmdb_ext/lmdb_ext.h
index cf52b64..7f1a784 100644
--- a/ext/lmdb_ext/lmdb_ext.h
+++ b/ext/lmdb_ext/lmdb_ext.h
@@ -59,6 +59,7 @@ typedef struct {
         MDB_env* env;
         VALUE    thread_txn_hash;
         VALUE    txn_thread_hash;
+        int      flags;
 } Environment;
 
 typedef struct {