diff --git a/arangod/Ahuacatl/ahuacatl-collections.c b/arangod/Ahuacatl/ahuacatl-collections.c
index 530630d08f..f0654d93f0 100644
--- a/arangod/Ahuacatl/ahuacatl-collections.c
+++ b/arangod/Ahuacatl/ahuacatl-collections.c
@@ -81,7 +81,7 @@ static TRI_aql_collection_t* CreateCollectionContainer (const char* const name)
   assert(name);
 
   collection = (TRI_aql_collection_t*) TRI_Allocate(TRI_UNKNOWN_MEM_ZONE, sizeof(TRI_aql_collection_t), false);
-  if (!collection) {
+  if (collection == NULL) {
     return NULL;
   }
 
@@ -109,12 +109,12 @@ bool SetupCollections (TRI_aql_context_t* const context) {
     char* name = context->_collectionNames._table[i];
     TRI_aql_collection_t* collection;
 
-    if (!name) {
+    if (! name) {
       continue;
     }
 
     collection = CreateCollectionContainer(name);
-    if (!collection) {
+    if (! collection) {
       result = false;
       TRI_SetErrorContextAql(context, TRI_ERROR_OUT_OF_MEMORY, NULL);
       break;
@@ -149,9 +149,9 @@ bool OpenCollections (TRI_aql_context_t* const context) {
 
     assert(collection);
     assert(collection->_name);
-    assert(!collection->_collection);
-    assert(!collection->_barrier);
-    assert(!collection->_readLocked);
+    assert(! collection->_collection);
+    assert(! collection->_barrier);
+    assert(! collection->_readLocked);
 
     LOG_TRACE("locking collection '%s'", collection->_name);
     collection->_collection = TRI_UseCollectionByNameVocBase(context->_vocbase, collection->_name);
@@ -357,11 +357,11 @@ void TRI_UnlockCollectionsAql (TRI_aql_context_t* const context) {
 ////////////////////////////////////////////////////////////////////////////////
 
 bool TRI_LockCollectionsAql (TRI_aql_context_t* const context) {
-  if (!SetupCollections(context)) {
+  if (! SetupCollections(context)) {
     return false;
   }
 
-  if (!OpenCollections(context)) {
+  if (! OpenCollections(context)) {
     TRI_UnlockCollectionsAql(context);
     return false;
   }
@@ -390,8 +390,8 @@ bool TRI_ReadLockCollectionsAql (TRI_aql_context_t* const context) {
     assert(collection->_name);
     assert(collection->_collection);
     assert(collection->_collection->_collection);
-    assert(!collection->_readLocked);
-    assert(!collection->_barrier);
+    assert(! collection->_readLocked);
+    assert(! collection->_barrier);
 
     primaryCollection = (TRI_primary_collection_t*) collection->_collection->_collection;
 
@@ -431,18 +431,18 @@ void TRI_ReadUnlockCollectionsAql (TRI_aql_context_t* const context) {
     assert(collection);
     assert(collection->_name);
 
-    if (!collection->_collection) {
+    if (! collection->_collection) {
       // don't unlock collections we weren't able to lock at all
       continue;
     }
 
-    if (!collection->_readLocked) {
+    if (! collection->_readLocked) {
       // don't unlock non-read-locked collections
       continue;
     }
     
     assert(collection->_collection->_collection);
-    assert(!collection->_barrier);
+    assert(! collection->_barrier);
 
     primaryCollection = (TRI_primary_collection_t*) collection->_collection->_collection;
 
diff --git a/arangod/Ahuacatl/ahuacatl-context.c b/arangod/Ahuacatl/ahuacatl-context.c
index 041d646ba1..d8b3c873e5 100644
--- a/arangod/Ahuacatl/ahuacatl-context.c
+++ b/arangod/Ahuacatl/ahuacatl-context.c
@@ -210,7 +210,7 @@ TRI_aql_context_t* TRI_CreateContextAql (TRI_vocbase_t* vocbase,
     return NULL;
   }
 
-  if (!TRI_InitParserAql(context)) {
+  if (! TRI_InitParserAql(context)) {
     // could not initialise the lexer
     TRI_FreeContextAql(context);
 
@@ -290,7 +290,7 @@ bool TRI_ValidateQueryContextAql (TRI_aql_context_t* const context) {
   }
 
   // parse the query
-  if (!TRI_ParseAql(context)) {
+  if (! TRI_ParseAql(context)) {
     // lexing/parsing failed
     return false;
   }
@@ -310,19 +310,19 @@ bool TRI_BindQueryContextAql (TRI_aql_context_t* const context,
                               const TRI_json_t* const parameters) {
 
   // add the bind parameters
-  if (!TRI_AddParameterValuesAql(context, parameters)) {
+  if (! TRI_AddParameterValuesAql(context, parameters)) {
     // adding parameters failed
     return false;
   }
   
   // validate the bind parameters used/passed
-  if (!TRI_ValidateBindParametersAql(context)) {
+  if (! TRI_ValidateBindParametersAql(context)) {
     // invalid bind parameters
     return false;
   }
 
   // inject the bind parameter values into the query AST
-  if (!TRI_InjectBindParametersAql(context)) {
+  if (! TRI_InjectBindParametersAql(context)) {
     // bind parameter injection failed
     return false;
   }
@@ -341,7 +341,7 @@ bool TRI_BindQueryContextAql (TRI_aql_context_t* const context,
 bool TRI_OptimiseQueryContextAql (TRI_aql_context_t* const context) {
 
   // do some basic optimisations in the AST
-  if (!TRI_OptimiseAql(context)) {
+  if (! TRI_OptimiseAql(context)) {
     // constant folding failed
     return false;
   }
@@ -364,17 +364,17 @@ bool TRI_OptimiseQueryContextAql (TRI_aql_context_t* const context) {
 
 bool TRI_LockQueryContextAql (TRI_aql_context_t* const context) {
   // mark all used collections as being used
-  if (!TRI_LockCollectionsAql(context)) {
+  if (! TRI_LockCollectionsAql(context)) {
     return false;
   }
 
   // acquire read locks on all collections used
-  if (!TRI_ReadLockCollectionsAql(context)) {
+  if (! TRI_ReadLockCollectionsAql(context)) {
     return false;
   }
   
   // add barriers for all collections used
-  if (!TRI_AddBarrierCollectionsAql(context)) {
+  if (! TRI_AddBarrierCollectionsAql(context)) {
     return false;
   }
   
@@ -421,7 +421,7 @@ char* TRI_RegisterStringAql (TRI_aql_context_t* const context,
     copy = TRI_DuplicateStringZ(TRI_UNKNOWN_MEM_ZONE, value);
   }
 
-  if (!copy) {
+  if (! copy) {
     ABORT_OOM
   }
 
diff --git a/arangod/VocBase/transaction.c b/arangod/VocBase/transaction.c
index 3b0bf858d1..677f14e578 100644
--- a/arangod/VocBase/transaction.c
+++ b/arangod/VocBase/transaction.c
@@ -412,7 +412,7 @@ void TRI_FreeTransactionContext (TRI_transaction_context_t* const context) {
   }
   TRI_DestroyAssociativePointer(&context->_collections);
 
-  // destroy mutexts
+  // destroy mutexes
   TRI_DestroyMutex(&context->_lock);
   TRI_DestroyMutex(&context->_collectionLock);
 
@@ -590,7 +590,6 @@ static int AcquireCollectionLocks (TRI_transaction_t* const trx) {
   context = trx->_context;
 
   n = trx->_collections._length;
-  assert(n > 0);
 
   // process collections in forward order
   for (i = 0; i < n; ++i) {
@@ -852,7 +851,6 @@ static int RegisterTransaction (TRI_transaction_t* const trx) {
   int res;
 
   assert(trx->_status == TRI_TRANSACTION_CREATED);
-  assert(trx->_collections._length > 0);
 
   context = trx->_context;
 
@@ -1161,10 +1159,6 @@ int TRI_StartTransaction (TRI_transaction_t* const trx, TRI_transaction_hint_t h
   
   assert(trx->_status == TRI_TRANSACTION_CREATED);
 
-  if (trx->_collections._length == 0) {
-    return TRI_ERROR_TRANSACTION_INCOMPLETE;
-  }
-
   trx->_hints = hints;
 
   res = AcquireCollectionLocks(trx);