diff --git a/dlls/winmm/mmsystem.c b/dlls/winmm/mmsystem.c
index 53d9055aa02..02eabef6cbc 100644
--- a/dlls/winmm/mmsystem.c
+++ b/dlls/winmm/mmsystem.c
@@ -1238,7 +1238,7 @@ UINT16 WINAPI waveOutGetErrorText16(UINT16 uError, LPSTR lpText, UINT16 uSize)
  *			waveOutOpen			[MMSYSTEM.404]
  */
 UINT16 WINAPI waveOutOpen16(HWAVEOUT16* lphWaveOut, UINT16 uDeviceID,
-                            const WAVEFORMATEX *lpFormat, DWORD dwCallback,
+                            LPCWAVEFORMATEX lpFormat, DWORD dwCallback,
 			    DWORD dwInstance, DWORD dwFlags)
 {
     HANDLE		hWaveOut;
@@ -1529,7 +1529,7 @@ UINT16 WINAPI waveInGetDevCaps16(UINT16 uDeviceID, LPWAVEINCAPS16 lpCaps,
  * 				waveInOpen			[MMSYSTEM.504]
  */
 UINT16 WINAPI waveInOpen16(HWAVEIN16* lphWaveIn, UINT16 uDeviceID,
-                           const WAVEFORMATEX *lpFormat, DWORD dwCallback,
+                           LPCWAVEFORMATEX lpFormat, DWORD dwCallback,
                            DWORD dwInstance, DWORD dwFlags)
 {
     HANDLE		hWaveIn;
diff --git a/tools/winapi/win16.api b/tools/winapi/win16.api
index 854ef32564b..11644c690b8 100644
--- a/tools/winapi/win16.api
+++ b/tools/winapi/win16.api
@@ -560,6 +560,7 @@ HWAVEIN16 *
 HWAVEOUT16 *
 LPAUXCAPS16
 LPBYTE
+LPCWAVEFORMATEX
 LPDWORD
 LPHANDLE16
 LPHMIXER16
@@ -579,7 +580,6 @@ LPMMTIME16
 LPTIMECAPS16
 LPUINT16
 LPVOID
-LPWAVEFORMATEX
 LPWAVEHDR
 LPWAVEINCAPS16
 LPWAVEOUTCAPS16