diff --git a/dlls/quartz/avidec.c b/dlls/quartz/avidec.c
index 68b1908d6e6..8469bbc9f29 100644
--- a/dlls/quartz/avidec.c
+++ b/dlls/quartz/avidec.c
@@ -203,7 +203,7 @@ static HRESULT AVIDec_ConnectInput(InputPin *pin, const AM_MEDIA_TYPE * pmt)
             bmi = &format2->bmiHeader;
         else
             goto failed;
-        TRACE("Fourcc: %s\n", debugstr_an((char *)&pmt->subtype.Data1, 4));
+        TRACE("Fourcc: %s\n", debugstr_an((const char *)&pmt->subtype.Data1, 4));
 
         This->hvid = ICLocate(pmt->majortype.Data1, pmt->subtype.Data1, bmi, NULL, ICMODE_DECOMPRESS);
         if (This->hvid)
diff --git a/dlls/quartz/avisplit.c b/dlls/quartz/avisplit.c
index faa844b4848..42ec2ae2b34 100644
--- a/dlls/quartz/avisplit.c
+++ b/dlls/quartz/avisplit.c
@@ -692,7 +692,7 @@ static HRESULT AVISplitter_ProcessStreamList(AVISplitterImpl * This, const BYTE
                     amt.formattype = FORMAT_WaveFormatEx;
                     break;
                 default:
-                    FIXME("fccType %.4s not handled yet\n", (char *)&pStrHdr->fccType);
+                    FIXME("fccType %.4s not handled yet\n", (const char *)&pStrHdr->fccType);
                     amt.formattype = FORMAT_None;
                 }
                 amt.majortype = MEDIATYPE_Video;
@@ -793,7 +793,7 @@ static HRESULT AVISplitter_ProcessStreamList(AVISplitterImpl * This, const BYTE
             TRACE("bIndexSubType: %hd\n", pIndex->bIndexSubType);
             TRACE("bIndexType: %hd\n", pIndex->bIndexType);
             TRACE("nEntriesInUse: %u\n", pIndex->nEntriesInUse);
-            TRACE("dwChunkId: %.4s\n", (char *)&pIndex->dwChunkId);
+            TRACE("dwChunkId: %.4s\n", (const char *)&pIndex->dwChunkId);
             if (pIndex->dwReserved[0])
                 TRACE("dwReserved[0]: %u\n", pIndex->dwReserved[0]);
             if (pIndex->dwReserved[2])