diff --git a/dlls/mfplat/buffer.c b/dlls/mfplat/buffer.c
index 27ae44a91ce..0d912a7afeb 100644
--- a/dlls/mfplat/buffer.c
+++ b/dlls/mfplat/buffer.c
@@ -311,7 +311,7 @@ static HRESULT WINAPI sample_CompareItem(IMFSample *iface, REFGUID key, REFPROPV
 {
     struct sample *sample = impl_from_IMFSample(iface);
 
-    TRACE("%p, %s, %p, %p.\n", iface, debugstr_attr(key), value, result);
+    TRACE("%p, %s, %s, %p.\n", iface, debugstr_attr(key), debugstr_propvar(value), result);
 
     return attributes_CompareItem(&sample->attributes, key, value, result);
 }
@@ -429,7 +429,7 @@ static HRESULT WINAPI sample_SetItem(IMFSample *iface, REFGUID key, REFPROPVARIA
 {
     struct sample *sample = impl_from_IMFSample(iface);
 
-    TRACE("%p, %s, %p.\n", iface, debugstr_attr(key), value);
+    TRACE("%p, %s, %s.\n", iface, debugstr_attr(key), debugstr_propvar(value));
 
     return attributes_SetItem(&sample->attributes, key, value);
 }
diff --git a/dlls/mfplat/main.c b/dlls/mfplat/main.c
index 14bde4a954f..abb269c26f0 100644
--- a/dlls/mfplat/main.c
+++ b/dlls/mfplat/main.c
@@ -1621,7 +1621,7 @@ static HRESULT WINAPI mfattributes_CompareItem(IMFAttributes *iface, REFGUID key
 {
     struct attributes *attributes = impl_from_IMFAttributes(iface);
 
-    TRACE("%p, %s, %p, %p.\n", iface, debugstr_attr(key), value, result);
+    TRACE("%p, %s, %s, %p.\n", iface, debugstr_attr(key), debugstr_propvar(value), result);
 
     return attributes_CompareItem(attributes, key, value, result);
 }
@@ -1741,7 +1741,7 @@ static HRESULT WINAPI mfattributes_SetItem(IMFAttributes *iface, REFGUID key, RE
 {
     struct attributes *attributes = impl_from_IMFAttributes(iface);
 
-    TRACE("%p, %s, %p.\n", iface, debugstr_attr(key), value);
+    TRACE("%p, %s, %s.\n", iface, debugstr_attr(key), debugstr_propvar(value));
 
     return attributes_SetItem(attributes, key, value);
 }
@@ -3779,11 +3779,12 @@ static HRESULT WINAPI bytestream_wrapper_events_EndGetEvent(IMFMediaEventGenerat
     return IMFMediaEventGenerator_EndGetEvent(wrapper->event_generator, result, event);
 }
 
-static HRESULT WINAPI bytestream_wrapper_events_QueueEvent(IMFMediaEventGenerator *iface, MediaEventType type, REFGUID ext_type, HRESULT hr, const PROPVARIANT *value)
+static HRESULT WINAPI bytestream_wrapper_events_QueueEvent(IMFMediaEventGenerator *iface, MediaEventType type,
+        REFGUID ext_type, HRESULT hr, const PROPVARIANT *value)
 {
     struct bytestream_wrapper *wrapper = impl_wrapper_from_IMFMediaEventGenerator(iface);
 
-    TRACE("%p, %d, %s, %#x, %p.\n", iface, type, debugstr_guid(ext_type), hr, value);
+    TRACE("%p, %d, %s, %#x, %s.\n", iface, type, debugstr_guid(ext_type), hr, debugstr_propvar(value));
 
     return IMFMediaEventGenerator_QueueEvent(wrapper->event_generator, type, ext_type, hr, value);
 }
@@ -3900,11 +3901,12 @@ static HRESULT WINAPI bytestream_wrapper_propstore_GetValue(IPropertyStore *ifac
     return IPropertyStore_GetValue(wrapper->propstore, key, value);
 }
 
-static HRESULT WINAPI bytestream_wrapper_propstore_SetValue(IPropertyStore *iface, REFPROPERTYKEY key, const PROPVARIANT *value)
+static HRESULT WINAPI bytestream_wrapper_propstore_SetValue(IPropertyStore *iface, REFPROPERTYKEY key,
+        const PROPVARIANT *value)
 {
     struct bytestream_wrapper *wrapper = impl_wrapper_from_IPropertyStore(iface);
 
-    TRACE("%p, %p, %p.\n", iface, key, value);
+    TRACE("%p, %p, %s.\n", iface, key, debugstr_propvar(value));
 
     return IPropertyStore_SetValue(wrapper->propstore, key, value);
 }
@@ -3966,11 +3968,12 @@ static HRESULT WINAPI bytestream_wrapper_attributes_GetItemType(IMFAttributes *i
     return IMFAttributes_GetItemType(wrapper->attributes, key, type);
 }
 
-static HRESULT WINAPI bytestream_wrapper_attributes_CompareItem(IMFAttributes *iface, REFGUID key, REFPROPVARIANT value, BOOL *result)
+static HRESULT WINAPI bytestream_wrapper_attributes_CompareItem(IMFAttributes *iface, REFGUID key,
+        REFPROPVARIANT value, BOOL *result)
 {
     struct bytestream_wrapper *wrapper = impl_wrapper_from_IMFAttributes(iface);
 
-    TRACE("%p, %s, %p, %p.\n", iface, debugstr_attr(key), value, result);
+    TRACE("%p, %s, %s, %p.\n", iface, debugstr_attr(key), debugstr_propvar(value), result);
 
     return IMFAttributes_CompareItem(wrapper->attributes, key, value, result);
 }
@@ -4090,7 +4093,7 @@ static HRESULT WINAPI bytestream_wrapper_attributes_SetItem(IMFAttributes *iface
 {
     struct bytestream_wrapper *wrapper = impl_wrapper_from_IMFAttributes(iface);
 
-    TRACE("%p, %s, %p.\n", iface, debugstr_attr(key), value);
+    TRACE("%p, %s, %s.\n", iface, debugstr_attr(key), debugstr_propvar(value));
 
     return IMFAttributes_SetItem(wrapper->attributes, key, value);
 }
@@ -5451,7 +5454,7 @@ static HRESULT WINAPI mfmediaevent_CompareItem(IMFMediaEvent *iface, REFGUID key
 {
     struct media_event *event = impl_from_IMFMediaEvent(iface);
 
-    TRACE("%p, %s, %p, %p.\n", iface, debugstr_attr(key), value, result);
+    TRACE("%p, %s, %s, %p.\n", iface, debugstr_attr(key), debugstr_propvar(value), result);
 
     return attributes_CompareItem(&event->attributes, key, value, result);
 }
@@ -5572,7 +5575,7 @@ static HRESULT WINAPI mfmediaevent_SetItem(IMFMediaEvent *iface, REFGUID key, RE
 {
     struct media_event *event = impl_from_IMFMediaEvent(iface);
 
-    TRACE("%p, %s, %p.\n", iface, debugstr_attr(key), value);
+    TRACE("%p, %s, %s.\n", iface, debugstr_attr(key), debugstr_propvar(value));
 
     return attributes_SetItem(&event->attributes, key, value);
 }
@@ -5789,13 +5792,14 @@ static const IMFMediaEventVtbl mfmediaevent_vtbl =
 /***********************************************************************
  *      MFCreateMediaEvent (mfplat.@)
  */
-HRESULT WINAPI MFCreateMediaEvent(MediaEventType type, REFGUID extended_type, HRESULT status,
-                                  const PROPVARIANT *value, IMFMediaEvent **event)
+HRESULT WINAPI MFCreateMediaEvent(MediaEventType type, REFGUID extended_type, HRESULT status, const PROPVARIANT *value,
+        IMFMediaEvent **event)
 {
     mfmediaevent *object;
     HRESULT hr;
 
-    TRACE("%s, %s, %08x, %p, %p\n", debugstr_eventid(type), debugstr_guid(extended_type), status, value, event);
+    TRACE("%s, %s, %08x, %p, %p\n", debugstr_eventid(type), debugstr_guid(extended_type), status,
+            debugstr_propvar(value), event);
 
     object = HeapAlloc( GetProcessHeap(), 0, sizeof(*object) );
     if(!object)
@@ -6069,7 +6073,8 @@ static HRESULT WINAPI eventqueue_QueueEventParamVar(IMFMediaEventQueue *iface, M
     IMFMediaEvent *event;
     HRESULT hr;
 
-    TRACE("%p, %s, %s, %#x, %p\n", iface, debugstr_eventid(event_type), debugstr_guid(extended_type), status, value);
+    TRACE("%p, %s, %s, %#x, %s\n", iface, debugstr_eventid(event_type), debugstr_guid(extended_type), status,
+            debugstr_propvar(value));
 
     if (FAILED(hr = MFCreateMediaEvent(event_type, extended_type, status, value, &event)))
         return hr;
diff --git a/dlls/mfplat/mediatype.c b/dlls/mfplat/mediatype.c
index f4a2577c3ac..aaf0714bdd0 100644
--- a/dlls/mfplat/mediatype.c
+++ b/dlls/mfplat/mediatype.c
@@ -149,7 +149,7 @@ static HRESULT WINAPI mediatype_CompareItem(IMFMediaType *iface, REFGUID key, RE
 {
     struct media_type *media_type = impl_from_IMFMediaType(iface);
 
-    TRACE("%p, %s, %p, %p.\n", iface, debugstr_attr(key), value, result);
+    TRACE("%p, %s, %s, %p.\n", iface, debugstr_attr(key), debugstr_propvar(value), result);
 
     return attributes_CompareItem(&media_type->attributes, key, value, result);
 }
@@ -270,7 +270,7 @@ static HRESULT WINAPI mediatype_SetItem(IMFMediaType *iface, REFGUID key, REFPRO
 {
     struct media_type *media_type = impl_from_IMFMediaType(iface);
 
-    TRACE("%p, %s, %p.\n", iface, debugstr_attr(key), value);
+    TRACE("%p, %s, %s.\n", iface, debugstr_attr(key), debugstr_propvar(value));
 
     return attributes_SetItem(&media_type->attributes, key, value);
 }
@@ -695,7 +695,7 @@ static HRESULT WINAPI stream_descriptor_CompareItem(IMFStreamDescriptor *iface,
 {
     struct stream_desc *stream_desc = impl_from_IMFStreamDescriptor(iface);
 
-    TRACE("%p, %s, %p, %p.\n", iface, debugstr_attr(key), value, result);
+    TRACE("%p, %s, %s, %p.\n", iface, debugstr_attr(key), debugstr_propvar(value), result);
 
     return attributes_CompareItem(&stream_desc->attributes, key, value, result);
 }
@@ -817,7 +817,7 @@ static HRESULT WINAPI stream_descriptor_SetItem(IMFStreamDescriptor *iface, REFG
 {
     struct stream_desc *stream_desc = impl_from_IMFStreamDescriptor(iface);
 
-    TRACE("%p, %s, %p.\n", iface, debugstr_attr(key), value);
+    TRACE("%p, %s, %s.\n", iface, debugstr_attr(key), debugstr_propvar(value));
 
     return attributes_SetItem(&stream_desc->attributes, key, value);
 }
@@ -1271,7 +1271,7 @@ static HRESULT WINAPI presentation_descriptor_CompareItem(IMFPresentationDescrip
 {
     struct presentation_desc *presentation_desc = impl_from_IMFPresentationDescriptor(iface);
 
-    TRACE("%p, %s, %p, %p.\n", iface, debugstr_attr(key), value, result);
+    TRACE("%p, %s, %s, %p.\n", iface, debugstr_attr(key), debugstr_propvar(value), result);
 
     return attributes_CompareItem(&presentation_desc->attributes, key, value, result);
 }
@@ -1396,7 +1396,7 @@ static HRESULT WINAPI presentation_descriptor_SetItem(IMFPresentationDescriptor
 {
     struct presentation_desc *presentation_desc = impl_from_IMFPresentationDescriptor(iface);
 
-    TRACE("%p, %s, %p.\n", iface, debugstr_attr(key), value);
+    TRACE("%p, %s, %s.\n", iface, debugstr_attr(key), debugstr_propvar(value));
 
     return attributes_SetItem(&presentation_desc->attributes, key, value);
 }
diff --git a/dlls/mfplat/mfplat_private.h b/dlls/mfplat/mfplat_private.h
index d7a7547f033..57e4211e40f 100644
--- a/dlls/mfplat/mfplat_private.h
+++ b/dlls/mfplat/mfplat_private.h
@@ -16,6 +16,8 @@
  * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA
  */
 
+#define NONAMELESSUNION
+
 #undef INITGUID
 #include <guiddef.h>
 #include "mfapi.h"
@@ -23,6 +25,7 @@
 #include "mferror.h"
 
 #include "wine/heap.h"
+#include "wine/debug.h"
 
 struct attribute
 {
@@ -114,3 +117,33 @@ static inline BOOL mf_array_reserve(void **elements, size_t *capacity, size_t co
 
     return TRUE;
 }
+
+static inline const char *debugstr_propvar(const PROPVARIANT *v)
+{
+    if (!v)
+        return "(null)";
+
+    switch (v->vt)
+    {
+        case VT_EMPTY:
+            return wine_dbg_sprintf("%p {VT_EMPTY}", v);
+        case VT_NULL:
+            return wine_dbg_sprintf("%p {VT_NULL}", v);
+        case VT_UI4:
+            return wine_dbg_sprintf("%p {VT_UI4: %d}", v, v->u.ulVal);
+        case VT_UI8:
+            return wine_dbg_sprintf("%p {VT_UI8: %s}", v, wine_dbgstr_longlong(v->u.uhVal.QuadPart));
+        case VT_R8:
+            return wine_dbg_sprintf("%p {VT_R8: %lf}", v, v->u.dblVal);
+        case VT_CLSID:
+            return wine_dbg_sprintf("%p {VT_CLSID: %s}", v, debugstr_guid(v->u.puuid));
+        case VT_LPWSTR:
+            return wine_dbg_sprintf("%p {VT_LPWSTR: %s}", v, wine_dbgstr_w(v->u.pwszVal));
+        case VT_VECTOR | VT_UI1:
+            return wine_dbg_sprintf("%p {VT_VECTOR|VT_UI1: %p}", v, v->u.caub.pElems);
+        case VT_UNKNOWN:
+            return wine_dbg_sprintf("%p {VT_UNKNOWN: %p}", v, v->u.punkVal);
+        default:
+            return wine_dbg_sprintf("%p {vt %#x}", v, v->vt);
+    }
+}
diff --git a/dlls/mfplat/queue.c b/dlls/mfplat/queue.c
index 36c50566d3b..31b281a9a3a 100644
--- a/dlls/mfplat/queue.c
+++ b/dlls/mfplat/queue.c
@@ -19,6 +19,7 @@
 #include <stdarg.h>
 
 #define COBJMACROS
+#define NONAMELESSUNION
 
 #include "wine/debug.h"
 #include "wine/list.h"