diff --git a/reactos/drivers/wdm/audio/backpln/portcls/irpstream.cpp b/reactos/drivers/wdm/audio/backpln/portcls/irpstream.cpp
index 62489cbab1a..ed55fa7c56f 100644
--- a/reactos/drivers/wdm/audio/backpln/portcls/irpstream.cpp
+++ b/reactos/drivers/wdm/audio/backpln/portcls/irpstream.cpp
@@ -57,6 +57,12 @@ protected:
 
 };
 
+typedef struct
+{
+    PVOID Tag;
+    UCHAR Used;
+}KSSTREAM_TAG, *PKSSTREAM_TAG;
+
 typedef struct
 {
     ULONG StreamHeaderCount;
@@ -65,7 +71,7 @@ typedef struct
 
     PKSSTREAM_HEADER CurStreamHeader;
     PVOID * Data;
-    PVOID * Tags;
+    PKSSTREAM_TAG Tags;
 }KSSTREAM_DATA, *PKSSTREAM_DATA;
 
 #define STREAM_DATA_OFFSET   (0)
@@ -208,7 +214,7 @@ CIrpQueue::AddMapping(
     if (m_TagSupportEnabled)
     {
         // allocate array for storing the pointers of the data */
-        StreamData->Tags = (PVOID*)AllocateItem(NonPagedPool, sizeof(PVOID) * StreamData->StreamHeaderCount, TAG_PORTCLASS);
+        StreamData->Tags = (PKSSTREAM_TAG)AllocateItem(NonPagedPool, sizeof(KSSTREAM_TAG) * StreamData->StreamHeaderCount, TAG_PORTCLASS);
         if (!StreamData->Data)
         {
             // out of memory
@@ -520,7 +526,6 @@ CIrpQueue::GetMappingWithTag(
     PKSSTREAM_DATA StreamData;
 
     /* sanity checks */
-    PC_ASSERT(Tag != NULL);
     PC_ASSERT(PhysicalAddress);
     PC_ASSERT(VirtualAddress);
     PC_ASSERT(ByteCount);
@@ -551,7 +556,11 @@ CIrpQueue::GetMappingWithTag(
     *VirtualAddress = StreamData->Data[StreamData->StreamHeaderIndex];
 
     // store tag in irp
-    StreamData->Tags[StreamData->StreamHeaderIndex] = Tag;
+    StreamData->Tags[StreamData->StreamHeaderIndex].Tag = Tag;
+    StreamData->Tags[StreamData->StreamHeaderIndex].Used = TRUE;
+
+    // increment header index
+    StreamData->StreamHeaderIndex++;
 
     // mapping size
     if (m_Descriptor->DataFlow == KSPIN_DATAFLOW_IN)
@@ -571,7 +580,7 @@ CIrpQueue::GetMappingWithTag(
         m_NumDataAvailable -= StreamData->CurStreamHeader->FrameExtent;
     }
 
-    if (StreamData->StreamHeaderIndex + 1 == StreamData->StreamHeaderCount)
+    if (StreamData->StreamHeaderIndex == StreamData->StreamHeaderCount)
     {
         // last mapping
         *Flags = 1;
@@ -588,9 +597,6 @@ CIrpQueue::GetMappingWithTag(
         // one more mapping in the irp
         *Flags = 0;
 
-        // increment header index
-        StreamData->StreamHeaderIndex++;
-
         // move to next header
         StreamData->CurStreamHeader = (PKSSTREAM_HEADER)((ULONG_PTR)StreamData->CurStreamHeader + StreamData->CurStreamHeader->Size);
     }
@@ -622,10 +628,11 @@ CIrpQueue::ReleaseMappingWithTag(
             for(Index = 0; Index < StreamData->StreamHeaderIndex; Index++)
             {
                 // check if it is the same tag
-                if (StreamData->Tags[Index] == Tag)
+                if (StreamData->Tags[Index].Tag == Tag && StreamData->Tags[Index].Used == TRUE)
                 {
                     // mark mapping as released
-                    StreamData->Tags[Index] = NULL;
+                    StreamData->Tags[Index].Tag = NULL;
+                    StreamData->Tags[Index].Used = FALSE;
 
                     // done
                     return STATUS_SUCCESS;
@@ -648,15 +655,17 @@ CIrpQueue::ReleaseMappingWithTag(
     StreamData = (PKSSTREAM_DATA)Irp->Tail.Overlay.DriverContext[STREAM_DATA_OFFSET];
 
     // sanity check
-    PC_ASSERT(StreamData->StreamHeaderIndex + 1 == StreamData->StreamHeaderCount);
+    PC_ASSERT(StreamData->StreamHeaderIndex == StreamData->StreamHeaderCount);
 
     // check if the released mapping is one of these
     for(Index = 0; Index < StreamData->StreamHeaderCount; Index++)
     {
-        if (StreamData->Tags[Index] == Tag)
+        if (StreamData->Tags[Index].Tag == Tag &&
+            StreamData->Tags[Index].Used == TRUE)
         {
             // mark mapping as released
-            StreamData->Tags[Index] = NULL;
+            StreamData->Tags[Index].Tag = NULL;
+            StreamData->Tags[Index].Used = FALSE;
 
             // done
             break;
@@ -668,7 +677,8 @@ CIrpQueue::ReleaseMappingWithTag(
             // therefore if the current mapping is not the searched one, it must have been already
             // released
             //
-            PC_ASSERT(StreamData->Tags[Index] == NULL);
+            ASSERT(StreamData->Tags[Index].Tag == NULL);
+            ASSERT(StreamData->Tags[Index].Used == FALSE);
         }
     }