diff --git a/DCMTKQueryNode.h b/DCMTKQueryNode.h
index 7edcd901b8..56a6df307c 100644
--- a/DCMTKQueryNode.h
+++ b/DCMTKQueryNode.h
@@ -79,7 +79,7 @@
 - (DCMCalendarDate *)time;
 - (NSString *)modality;
 - (NSNumber *)numberImages;
-- (NSMutableArray *)children;
+- (NSArray *)children;
 - (void) setChildren: (NSArray *) c;
 - (void)purgeChildren;
 - (void)addChild:(DcmDataset *)dataset;
diff --git a/DCMTKQueryNode.mm b/DCMTKQueryNode.mm
index 9ffdf943e3..d9fe4bc315 100644
--- a/DCMTKQueryNode.mm
+++ b/DCMTKQueryNode.mm
@@ -518,7 +518,7 @@ - (NSString *)modality{
 - (NSNumber *)numberImages{
 	return _numberImages;
 }
-- (NSMutableArray *)children
+- (NSArray *)children
 {
     @synchronized( _children)
     {
@@ -977,8 +977,6 @@ - (void) WADORetrieve: (DCMTKStudyQueryNode*) study // requestService: WFIND?
             N2LogExceptionWithStackTrace(e);
     }
 	
-	NSMutableArray *urlToDownload = [NSMutableArray array];
-	
 	if( [self isKindOfClass:[DCMTKStudyQueryNode class]])
 	{
 		// We are at STUDY level, and we want to go direclty to IMAGE level
@@ -1013,6 +1011,7 @@ - (void) WADORetrieve: (DCMTKStudyQueryNode*) study // requestService: WFIND?
                     [_children removeAllObjects];
                 }
                 
+                NSMutableArray *urlToDownload = [NSMutableArray array];
                 @try
                 {
                     childrenArray = [childrenArray sortedArrayUsingDescriptors: [NSArray arrayWithObjects: [NSSortDescriptor sortDescriptorWithKey: @"seriesInstanceUID" ascending: YES], nil]];
@@ -1043,8 +1042,6 @@ - (void) WADORetrieve: (DCMTKStudyQueryNode*) study // requestService: WFIND?
                 
                 self.countOfSuboperations += urlToDownload.count;
                 self.countOfSuccessfulSuboperations += downloader.countOfSuccesses;
-                
-                [urlToDownload removeAllObjects];
             }
         }
         
@@ -1067,6 +1064,8 @@ - (void) WADORetrieve: (DCMTKStudyQueryNode*) study // requestService: WFIND?
             childrenArray = [self children];
         }
         
+        NSMutableArray *urlToDownload = [NSMutableArray array];
+        
         @try
         {
             for( DCMTKQueryNode *image in childrenArray)
diff --git a/DCMTKStudyQueryNode.mm b/DCMTKStudyQueryNode.mm
index a1ce8e2337..9d88af8e70 100644
--- a/DCMTKStudyQueryNode.mm
+++ b/DCMTKStudyQueryNode.mm
@@ -398,7 +398,7 @@ - (id)valueForUndefinedKey:(NSString *)key
     return nil;
 }
 
-- (NSMutableArray*)children // instead of sorting after every addChild, we sort when the array is requested
+- (NSArray*)children // instead of sorting after every addChild, we sort when the array is requested
 {
     @synchronized( _children)
     {