diff --git a/README.md b/README.md
index f8dc310..c6335d4 100644
--- a/README.md
+++ b/README.md
@@ -28,7 +28,7 @@ Read our [getting started guide](https://docs.nextgraph.org/en/getting-started/)
 
 ## For contributors
 
-- [Install Rust](https://www.rust-lang.org/tools/install) minimum required 1.64.0
+- [Install Rust](https://www.rust-lang.org/tools/install) minimum required MSRV 1.64.0
 - [Install Nodejs](https://nodejs.org/en/download/)
 
 until this [PR](https://github.com/rustwasm/wasm-pack/pull/1271) is accepted, will have to install wasm-pack this way:
diff --git a/p2p-broker/src/broker_store/account.rs b/p2p-broker/src/broker_store/account.rs
index aa40791..30ee14e 100644
--- a/p2p-broker/src/broker_store/account.rs
+++ b/p2p-broker/src/broker_store/account.rs
@@ -116,7 +116,7 @@ impl<'a> Account<'a> {
 
         let info_ser = to_vec(info)?;
 
-        self.store.write_transaction(&|tx| {
+        self.store.write_transaction(&mut |tx| {
             if tx
                 .has_property_value(
                     Self::PREFIX,
@@ -218,7 +218,7 @@ impl<'a> Account<'a> {
     }
 
     pub fn del(&self) -> Result<(), StorageError> {
-        self.store.write_transaction(&|tx| {
+        self.store.write_transaction(&mut |tx| {
             if let Ok(clients) = tx.get_all(Self::PREFIX, &to_vec(&self.id)?, Some(Self::CLIENT)) {
                 for client in clients {
                     tx.del_all(Self::PREFIX_CLIENT, &client, &Self::ALL_CLIENT_PROPERTIES)?;
diff --git a/p2p-broker/src/broker_store/invitation.rs b/p2p-broker/src/broker_store/invitation.rs
index e53aead..4ed1340 100644
--- a/p2p-broker/src/broker_store/invitation.rs
+++ b/p2p-broker/src/broker_store/invitation.rs
@@ -74,7 +74,7 @@ impl<'a> Invitation<'a> {
             return Err(StorageError::BackendError);
         }
         let mut value = to_vec(&(code_type, expiry, memo.clone()))?;
-        store.write_transaction(&|tx| {
+        store.write_transaction(&mut |tx| {
             tx.put(Self::PREFIX, &to_vec(code)?, Some(Self::TYPE), &value)?;
             Ok(())
         })?;
@@ -168,7 +168,7 @@ impl<'a> Invitation<'a> {
     }
 
     pub fn del(&self) -> Result<(), StorageError> {
-        self.store.write_transaction(&|tx| {
+        self.store.write_transaction(&mut |tx| {
             tx.del_all(Self::PREFIX, &to_vec(&self.id)?, &Self::ALL_PROPERTIES)?;
             Ok(())
         })
diff --git a/p2p-broker/src/broker_store/overlay.rs b/p2p-broker/src/broker_store/overlay.rs
index 3347688..b18a694 100644
--- a/p2p-broker/src/broker_store/overlay.rs
+++ b/p2p-broker/src/broker_store/overlay.rs
@@ -73,7 +73,7 @@ impl<'a> Overlay<'a> {
         if acc.exists() {
             return Err(StorageError::BackendError);
         }
-        store.write_transaction(&|tx| {
+        store.write_transaction(&mut |tx| {
             tx.put(
                 Self::PREFIX,
                 &to_vec(&id)?,
diff --git a/p2p-broker/src/broker_store/peer.rs b/p2p-broker/src/broker_store/peer.rs
index 1e5240c..fea8648 100644
--- a/p2p-broker/src/broker_store/peer.rs
+++ b/p2p-broker/src/broker_store/peer.rs
@@ -71,7 +71,7 @@ impl<'a> Peer<'a> {
         if acc.exists() {
             return Err(StorageError::BackendError);
         }
-        store.write_transaction(&|tx| {
+        store.write_transaction(&mut |tx| {
             tx.put(
                 Self::PREFIX,
                 &to_vec(&id)?,
@@ -128,7 +128,7 @@ impl<'a> Peer<'a> {
         if current_advert.version() >= advert.version() {
             return Ok(());
         }
-        self.store.write_transaction(&|tx| {
+        self.store.write_transaction(&mut |tx| {
             tx.replace(
                 Self::PREFIX,
                 &to_vec(&self.id)?,
diff --git a/p2p-broker/src/broker_store/wallet.rs b/p2p-broker/src/broker_store/wallet.rs
index 8b0fc34..fc12933 100644
--- a/p2p-broker/src/broker_store/wallet.rs
+++ b/p2p-broker/src/broker_store/wallet.rs
@@ -11,6 +11,7 @@
 
 use p2p_net::types::*;
 use p2p_repo::kcv_store::KCVStore;
+use p2p_repo::kcv_store::WriteTransaction;
 use p2p_repo::log::*;
 use p2p_repo::store::*;
 use p2p_repo::types::*;
@@ -44,28 +45,30 @@ impl<'a> Wallet<'a> {
         prefix: u8,
         key: &Vec<u8>,
     ) -> Result<SymKey, StorageError> {
-        // FIXME. this get or create is not using a transaction, because calls will be made from the broker, that is behind a mutex.
-        // if this was to change, we should make the get and put inside one transaction.
-        let get = self
-            .store
-            .get(prefix, key, Some(Self::SUFFIX_FOR_EXIST_CHECK));
-        match get {
-            Err(e) => {
-                if e == StorageError::NotFound {
-                    self.create_single_key(prefix, key)
-                } else {
-                    log_debug!("Error while creating single key {}", e);
-                    Err(StorageError::BackendError)
+        let mut result: Option<SymKey> = None;
+        self.store.write_transaction(&mut |tx| {
+            let got = tx.get(prefix, key, Some(Self::SUFFIX_FOR_EXIST_CHECK));
+            match got {
+                Err(e) => {
+                    if e == StorageError::NotFound {
+                        let res = Self::create_single_key(tx, prefix, key)?;
+                        result = Some(res);
+                    } else {
+                        log_debug!("Error while creating single key {}", e);
+                        return Err(StorageError::BackendError);
+                    }
+                }
+                Ok(p) => {
+                    let k: SymKey = p
+                        .as_slice()
+                        .try_into()
+                        .map_err(|_| StorageError::BackendError)?;
+                    result = Some(k);
                 }
             }
-            Ok(p) => {
-                let k: SymKey = p
-                    .as_slice()
-                    .try_into()
-                    .map_err(|_| StorageError::BackendError)?;
-                Ok(k)
-            }
-        }
+            Ok(())
+        })?;
+        Ok(result.unwrap())
     }
 
     pub fn get_or_create_user_key(&self, user: &UserId) -> Result<SymKey, StorageError> {
@@ -76,10 +79,14 @@ impl<'a> Wallet<'a> {
         self.get_or_create_single_key(Self::PREFIX_USER, &to_vec(overlay)?)
     }
 
-    pub fn create_single_key(&self, prefix: u8, key: &Vec<u8>) -> Result<SymKey, StorageError> {
+    pub fn create_single_key(
+        tx: &mut dyn WriteTransaction,
+        prefix: u8,
+        key: &Vec<u8>,
+    ) -> Result<SymKey, StorageError> {
         let symkey = SymKey::random();
         let vec = symkey.slice().to_vec();
-        self.store.put(prefix, key, Some(Self::SYM_KEY), vec)?;
+        tx.put(prefix, key, Some(Self::SYM_KEY), &vec)?;
         Ok(symkey)
     }
     pub fn exists_single_key(&self, prefix: u8, key: &Vec<u8>) -> bool {
@@ -92,7 +99,13 @@ impl<'a> Wallet<'a> {
         self.exists_single_key(Self::PREFIX, &Self::KEY_ACCOUNTS.to_vec())
     }
     pub fn create_accounts_key(&self) -> Result<SymKey, StorageError> {
-        self.create_single_key(Self::PREFIX, &Self::KEY_ACCOUNTS.to_vec())
+        let mut result: Option<SymKey> = None;
+        self.store.write_transaction(&mut |tx| {
+            let res = Self::create_single_key(tx, Self::PREFIX, &Self::KEY_ACCOUNTS.to_vec())?;
+            result = Some(res);
+            Ok(())
+        })?;
+        Ok(result.unwrap())
     }
     pub fn get_or_create_peers_key(&self) -> Result<SymKey, StorageError> {
         self.get_or_create_single_key(Self::PREFIX, &Self::KEY_PEERS.to_vec())
diff --git a/p2p-repo/src/kcv_store.rs b/p2p-repo/src/kcv_store.rs
index afa4ee2..502e32c 100644
--- a/p2p-repo/src/kcv_store.rs
+++ b/p2p-repo/src/kcv_store.rs
@@ -81,7 +81,7 @@ pub trait ReadTransaction {
 pub trait KCVStore: ReadTransaction {
     fn write_transaction(
         &self,
-        method: &dyn Fn(&mut dyn WriteTransaction) -> Result<(), StorageError>,
+        method: &mut dyn FnMut(&mut dyn WriteTransaction) -> Result<(), StorageError>,
     ) -> Result<(), StorageError>;
 
     /// Save a property value to the store.
diff --git a/stores-lmdb/src/kcv_store.rs b/stores-lmdb/src/kcv_store.rs
index ae00520..a7729b4 100644
--- a/stores-lmdb/src/kcv_store.rs
+++ b/stores-lmdb/src/kcv_store.rs
@@ -364,7 +364,7 @@ impl ReadTransaction for LmdbKCVStore {
 impl KCVStore for LmdbKCVStore {
     fn write_transaction(
         &self,
-        method: &dyn Fn(&mut dyn WriteTransaction) -> Result<(), StorageError>,
+        method: &mut dyn FnMut(&mut dyn WriteTransaction) -> Result<(), StorageError>,
     ) -> Result<(), StorageError> {
         let lock = self.environment.read().unwrap();
         let writer = lock.write().unwrap();
@@ -389,7 +389,7 @@ impl KCVStore for LmdbKCVStore {
         suffix: Option<u8>,
         value: Vec<u8>,
     ) -> Result<(), StorageError> {
-        self.write_transaction(&|tx| tx.put(prefix, key, suffix, &value))
+        self.write_transaction(&mut |tx| tx.put(prefix, key, suffix, &value))
     }
 
     /// Replace the property of a key (single value) to the store.
@@ -400,12 +400,12 @@ impl KCVStore for LmdbKCVStore {
         suffix: Option<u8>,
         value: Vec<u8>,
     ) -> Result<(), StorageError> {
-        self.write_transaction(&|tx| tx.replace(prefix, key, suffix, &value))
+        self.write_transaction(&mut |tx| tx.replace(prefix, key, suffix, &value))
     }
 
     /// Delete a property from the store.
     fn del(&self, prefix: u8, key: &Vec<u8>, suffix: Option<u8>) -> Result<(), StorageError> {
-        self.write_transaction(&|tx| tx.del(prefix, key, suffix))
+        self.write_transaction(&mut |tx| tx.del(prefix, key, suffix))
     }
 
     /// Delete a specific value for a property from the store.
@@ -416,7 +416,7 @@ impl KCVStore for LmdbKCVStore {
         suffix: Option<u8>,
         value: Vec<u8>,
     ) -> Result<(), StorageError> {
-        self.write_transaction(&|tx| tx.del_property_value(prefix, key, suffix, &value))
+        self.write_transaction(&mut |tx| tx.del_property_value(prefix, key, suffix, &value))
     }
 
     /// Delete all properties of a key from the store.