diff --git a/reactos/include/psdk/mmreg.h b/reactos/include/psdk/mmreg.h
index ea38f6adbf3..ad7c9220585 100644
--- a/reactos/include/psdk/mmreg.h
+++ b/reactos/include/psdk/mmreg.h
@@ -137,6 +137,18 @@ typedef const struct _WAVEFORMATEX *LPCWAVEFORMATEX;
 #define   MM_UNMAPPED                   0xffff
 #define   MM_PID_UNMAPPED               MM_UNMAPPED
 
+#ifndef MM_MICROSOFT
+#define MM_MICROSOFT 0x01
+#endif
+#define MM_MSFT_ACM_MSADPCM 0x21
+#define MM_MSFT_ACM_IMAADPCM 0x22
+#define MM_MSFT_ACM_GSM610 0x24
+#define MM_MSFT_ACM_G711 0x25
+#define MM_MSFT_ACM_PCM 0x26
+
+#define MM_FRAUNHOFER_IIS 0xAC
+#define MM_FHGIIS_MPEGLAYER3_DECODE 0x09
+
 #if !defined(WAVE_FORMAT_EXTENSIBLE)
 #define  WAVE_FORMAT_EXTENSIBLE			0xFFFE  /* Microsoft */
 #endif
diff --git a/reactos/include/psdk/mmsystem.h b/reactos/include/psdk/mmsystem.h
index b32476a0bf6..b97e2ad4bc3 100644
--- a/reactos/include/psdk/mmsystem.h
+++ b/reactos/include/psdk/mmsystem.h
@@ -38,7 +38,10 @@ extern "C" {
 #define mmioFOURCC(c0,c1,c2,c3) MAKEFOURCC(c0,c1,c2,c3)
 #endif
 
+#ifndef MM_MICROSOFT
 #define MM_MICROSOFT            1       /* Microsoft Corp. */
+#endif
+
 #define MM_CREATIVE             2       /* Creative labs   */
 
 #define MM_JOY1MOVE           0x3A0