diff --git a/src/plugins/directshow/player/directshowiosource.cpp b/src/plugins/directshow/player/directshowiosource.cpp
index 3a4e1075..424120fd 100644
--- a/src/plugins/directshow/player/directshowiosource.cpp
+++ b/src/plugins/directshow/player/directshowiosource.cpp
@@ -99,6 +99,9 @@ void DirectShowIOSource::setDevice(QIODevice *device)
 
 void DirectShowIOSource::setAllocator(IMemAllocator *allocator)
 {
+    if (m_allocator == allocator)
+        return;
+
     if (m_allocator)
         m_allocator->Release();