diff --git a/dlls/amstream/amstream.c b/dlls/amstream/amstream.c
index 6c544f64ccf..a709c7b5b5b 100644
--- a/dlls/amstream/amstream.c
+++ b/dlls/amstream/amstream.c
@@ -129,7 +129,7 @@ static HRESULT WINAPI IAMMultiMediaStreamImpl_GetMediaStream(IAMMultiMediaStream
     MSPID PurposeId;
     unsigned int i;
 
-    TRACE("(%p/%p)->(%p,%p)\n", This, iface, idPurpose, ppMediaStream);
+    TRACE("(%p/%p)->(%s,%p)\n", This, iface, debugstr_guid(idPurpose), ppMediaStream);
 
     for (i = 0; i < This->nbStreams; i++)
     {
@@ -268,7 +268,7 @@ static HRESULT WINAPI IAMMultiMediaStreamImpl_AddMediaStream(IAMMultiMediaStream
     IMediaStream* pStream;
     IMediaStream** pNewStreams;
 
-    FIXME("(%p/%p)->(%p,%p,%x,%p) partial stub!\n", This, iface, pStreamObject, PurposeId, dwFlags, ppNewStream);
+    FIXME("(%p/%p)->(%p,%s,%x,%p) partial stub!\n", This, iface, pStreamObject, debugstr_guid(PurposeId), dwFlags, ppNewStream);
 
     if (IsEqualGUID(PurposeId, &MSPID_PrimaryVideo))
         hr = DirectDrawMediaStream_create((IMultiMediaStream*)iface, PurposeId, This->StreamType, &pStream);
diff --git a/dlls/amstream/mediastream.c b/dlls/amstream/mediastream.c
index 39e9a280957..697b03bdff1 100644
--- a/dlls/amstream/mediastream.c
+++ b/dlls/amstream/mediastream.c
@@ -58,7 +58,7 @@ HRESULT MediaStream_create(IMultiMediaStream* Parent, const MSPID* pPurposeId, S
 {
     IMediaStreamImpl* object; 
 
-    TRACE("(%p,%p,%p)\n", Parent, pPurposeId, ppMediaStream);
+    TRACE("(%p,%s,%p)\n", Parent, debugstr_guid(pPurposeId), ppMediaStream);
 
     object = HeapAlloc(GetProcessHeap(), HEAP_ZERO_MEMORY, sizeof(IMediaStreamImpl));
     if (!object)
@@ -198,7 +198,7 @@ HRESULT DirectDrawMediaStream_create(IMultiMediaStream* Parent, const MSPID* pPu
 {
     IDirectDrawMediaStreamImpl* object;
 
-    TRACE("(%p,%p,%p)\n", Parent, pPurposeId, ppMediaStream);
+    TRACE("(%p,%s,%p)\n", Parent, debugstr_guid(pPurposeId), ppMediaStream);
 
     object = HeapAlloc(GetProcessHeap(), HEAP_ZERO_MEMORY, sizeof(IMediaStreamImpl));
     if (!object)