diff --git a/arangod/Utils/AhuacatlTransaction.h b/arangod/Utils/AhuacatlTransaction.h
index d739dea795..eaee1df793 100644
--- a/arangod/Utils/AhuacatlTransaction.h
+++ b/arangod/Utils/AhuacatlTransaction.h
@@ -66,7 +66,7 @@ namespace triagens {
                              TRI_aql_context_t* const context) :
           Transaction<T>(vocbase, resolver) {
 
-          this->addHint(TRI_TRANSACTION_HINT_MANAGE_LOCKS);
+          this->addHint(TRI_TRANSACTION_HINT_IMPLICIT_LOCK);
 
           TRI_vector_pointer_t* collections = &context->_collections;
 
diff --git a/arangod/Utils/Transaction.h b/arangod/Utils/Transaction.h
index 4dc631d9f2..808e15234a 100644
--- a/arangod/Utils/Transaction.h
+++ b/arangod/Utils/Transaction.h
@@ -349,10 +349,7 @@ namespace triagens {
             return TRI_ERROR_INTERNAL;
           }
 
-          if ((this->status() == TRI_TRANSACTION_RUNNING && ! this->isEmbedded()) ||
-              this->status() == TRI_TRANSACTION_COMMITTED || 
-              this->status() == TRI_TRANSACTION_ABORTED || 
-              this->status() == TRI_TRANSACTION_FINISHED) {
+          if (this->status() != TRI_TRANSACTION_RUNNING) {
             return TRI_ERROR_TRANSACTION_INVALID_STATE;
           }
 
@@ -361,14 +358,7 @@ namespace triagens {
             return TRI_ERROR_NO_ERROR;
           }
 
-          if (type == TRI_TRANSACTION_READ) {
-            primary->beginRead(primary);
-          }
-          else {
-            primary->beginWrite(primary);
-          }
-
-          return TRI_ERROR_NO_ERROR;
+          return TRI_LockCollectionTransaction(this->_trx, (TRI_transaction_cid_t) primary->base._info._cid, type);
         }
 
 ////////////////////////////////////////////////////////////////////////////////
@@ -381,10 +371,7 @@ namespace triagens {
             return TRI_ERROR_INTERNAL;
           }
 
-          if ((this->status() == TRI_TRANSACTION_RUNNING && ! this->isEmbedded()) ||
-              this->status() == TRI_TRANSACTION_COMMITTED || 
-              this->status() == TRI_TRANSACTION_ABORTED || 
-              this->status() == TRI_TRANSACTION_FINISHED) {
+          if (this->status() != TRI_TRANSACTION_RUNNING) {
             return TRI_ERROR_TRANSACTION_INVALID_STATE;
           }
 
@@ -392,15 +379,8 @@ namespace triagens {
             // locking is a no-op in embedded transactions
             return TRI_ERROR_NO_ERROR;
           }
-
-          if (type == TRI_TRANSACTION_READ) {
-            primary->endRead(primary);
-          }
-          else {
-            primary->endWrite(primary);
-          }
-
-          return TRI_ERROR_NO_ERROR;
+          
+          return TRI_UnlockCollectionTransaction(this->_trx, (TRI_transaction_cid_t) primary->base._info._cid, type);
         }
 
 ////////////////////////////////////////////////////////////////////////////////
diff --git a/arangod/Utils/UserTransaction.h b/arangod/Utils/UserTransaction.h
index 53fbd2bb4b..bad24b212b 100644
--- a/arangod/Utils/UserTransaction.h
+++ b/arangod/Utils/UserTransaction.h
@@ -65,7 +65,7 @@ namespace triagens {
                          const vector<string>& writeCollections) : 
           Transaction<T>(vocbase, resolver) {
 
-          this->addHint(TRI_TRANSACTION_HINT_MANAGE_LOCKS);
+          this->addHint(TRI_TRANSACTION_HINT_IMPLICIT_LOCK);
 
           for (size_t i = 0; i < readCollections.size(); ++i) {
             this->addCollection(readCollections[i], TRI_TRANSACTION_READ);
diff --git a/arangod/VocBase/transaction.c b/arangod/VocBase/transaction.c
index f2d6a3917f..7c110cf65a 100644
--- a/arangod/VocBase/transaction.c
+++ b/arangod/VocBase/transaction.c
@@ -533,6 +533,60 @@ static void FreeCollection (TRI_transaction_collection_t* collection) {
   TRI_Free(TRI_UNKNOWN_MEM_ZONE, collection);
 }
 
+////////////////////////////////////////////////////////////////////////////////
+/// @brief lock a collection
+////////////////////////////////////////////////////////////////////////////////
+
+static int LockCollection (TRI_transaction_collection_t* collection,
+                          const TRI_transaction_type_e type) {
+  TRI_primary_collection_t* primary;
+
+  assert(collection != NULL);
+  assert(collection->_collection != NULL);
+  assert(collection->_collection->_collection != NULL);
+  assert(collection->_locked == false);
+
+  primary = collection->_collection->_collection;
+
+  if (type == TRI_TRANSACTION_READ) {
+    primary->beginRead(primary);
+  }
+  else {
+    primary->beginWrite(primary);
+  }
+
+  collection->_locked = true;
+
+  return TRI_ERROR_NO_ERROR;
+}
+
+////////////////////////////////////////////////////////////////////////////////
+/// @brief unlock a collection
+////////////////////////////////////////////////////////////////////////////////
+
+static int UnlockCollection (TRI_transaction_collection_t* collection,
+                          const TRI_transaction_type_e type) {
+  TRI_primary_collection_t* primary;
+
+  assert(collection != NULL);
+  assert(collection->_collection != NULL);
+  assert(collection->_collection->_collection != NULL);
+  assert(collection->_locked == true);
+
+  primary = collection->_collection->_collection;
+
+  if (type == TRI_TRANSACTION_READ) {
+    primary->endRead(primary);
+  }
+  else {
+    primary->endWrite(primary);
+  }
+
+  collection->_locked = false;
+  
+  return TRI_ERROR_NO_ERROR;
+}
+
 ////////////////////////////////////////////////////////////////////////////////
 /// @brief return a global instance for the collection
 /// this function will create a global instance if it does not yet exist
@@ -599,17 +653,12 @@ static int UseCollections (TRI_transaction_t* const trx) {
       collection->_globalLock = true;
     }
  
-    if ((trx->_hints & (TRI_transaction_hint_t) TRI_TRANSACTION_HINT_MANAGE_LOCKS) != 0) {
-      TRI_primary_collection_t* primary = (TRI_primary_collection_t*) collection->_collection->_collection;
+    if ((trx->_hints & (TRI_transaction_hint_t) TRI_TRANSACTION_HINT_IMPLICIT_LOCK) != 0) {
+      int res = LockCollection(collection, collection->_type);
 
-      if (collection->_type == TRI_TRANSACTION_WRITE) {
-        primary->beginWrite(primary);
+      if (res != TRI_ERROR_NO_ERROR) {
+        return res;
       }
-      else if (collection->_type == TRI_TRANSACTION_READ) {
-        primary->beginRead(primary);
-      }
-
-      collection->_locked = true;
     }
   }
 
@@ -639,18 +688,8 @@ static int ReleaseCollections (TRI_transaction_t* const trx) {
       continue;
     }
     
-    if (collection->_locked && 
-        (trx->_hints & (TRI_transaction_hint_t) TRI_TRANSACTION_HINT_MANAGE_LOCKS) != 0) {
-      
-      TRI_primary_collection_t* primary = (TRI_primary_collection_t*) collection->_collection->_collection;
-      if (collection->_type == TRI_TRANSACTION_WRITE) {
-        primary->endWrite(primary);
-      }
-      else if (collection->_type == TRI_TRANSACTION_READ) {
-        primary->endRead(primary);
-      }
-
-      collection->_locked = false;
+    if (collection->_locked) { 
+      UnlockCollection(collection, collection->_type);
     }
 
     if (collection->_type == TRI_TRANSACTION_WRITE && collection->_globalLock) {
@@ -971,6 +1010,58 @@ void TRI_FreeTransaction (TRI_transaction_t* const trx) {
 /// @{
 ////////////////////////////////////////////////////////////////////////////////
 
+////////////////////////////////////////////////////////////////////////////////
+/// @brief request a lock for a collection
+////////////////////////////////////////////////////////////////////////////////
+
+int TRI_LockCollectionTransaction (TRI_transaction_t* const trx,
+                                   const TRI_transaction_cid_t cid,
+                                   const TRI_transaction_type_e type) {
+  size_t i, n;
+
+  n = trx->_collections._length;
+
+  for (i = 0; i < n; ++i) {
+    TRI_transaction_collection_t* collection = TRI_AtVectorPointer(&trx->_collections, i);
+
+    if (collection->_collection == NULL) {
+      continue;
+    }
+
+    if (collection->_cid == cid) {
+      return LockCollection(collection, type);
+    }
+  }
+
+  return TRI_ERROR_ARANGO_COLLECTION_NOT_FOUND;
+}
+
+////////////////////////////////////////////////////////////////////////////////
+/// @brief request an unlock for a collection
+////////////////////////////////////////////////////////////////////////////////
+
+int TRI_UnlockCollectionTransaction (TRI_transaction_t* const trx,
+                                     const TRI_transaction_cid_t cid,
+                                     const TRI_transaction_type_e type) {
+  size_t i, n;
+
+  n = trx->_collections._length;
+
+  for (i = 0; i < n; ++i) {
+    TRI_transaction_collection_t* collection = TRI_AtVectorPointer(&trx->_collections, i);
+
+    if (collection->_collection == NULL) {
+      continue;
+    }
+
+    if (collection->_cid == cid) {
+      return UnlockCollection(collection, type);
+    }
+  }
+
+  return TRI_ERROR_ARANGO_COLLECTION_NOT_FOUND;
+}
+
 ////////////////////////////////////////////////////////////////////////////////
 /// @brief return whether the transaction consists only of a single operation
 ////////////////////////////////////////////////////////////////////////////////
diff --git a/arangod/VocBase/transaction.h b/arangod/VocBase/transaction.h
index d8979dade9..11ffd9e82e 100644
--- a/arangod/VocBase/transaction.h
+++ b/arangod/VocBase/transaction.h
@@ -303,7 +303,7 @@ typedef uint32_t TRI_transaction_hint_t;
 typedef enum {
   TRI_TRANSACTION_HINT_NONE             = 0,
   TRI_TRANSACTION_HINT_SINGLE_OPERATION = 1,
-  TRI_TRANSACTION_HINT_MANAGE_LOCKS     = 2
+  TRI_TRANSACTION_HINT_IMPLICIT_LOCK    = 2
 }
 TRI_transaction_hint_e;
 
@@ -401,6 +401,22 @@ int TRI_AddCollectionTransaction (TRI_transaction_t* const,
                                   const TRI_transaction_cid_t, 
                                   const TRI_transaction_type_e);
 
+////////////////////////////////////////////////////////////////////////////////
+/// @brief request a lock for a collection
+////////////////////////////////////////////////////////////////////////////////
+
+int TRI_LockCollectionTransaction (TRI_transaction_t* const,
+                                   const TRI_transaction_cid_t,
+                                   const TRI_transaction_type_e);
+
+////////////////////////////////////////////////////////////////////////////////
+/// @brief request an unlock for a collection
+////////////////////////////////////////////////////////////////////////////////
+
+int TRI_UnlockCollectionTransaction (TRI_transaction_t* const,
+                                     const TRI_transaction_cid_t,
+                                     const TRI_transaction_type_e);
+
 ////////////////////////////////////////////////////////////////////////////////
 /// @brief start a transaction
 ////////////////////////////////////////////////////////////////////////////////