diff --git a/dlls/msacm32/internal.c b/dlls/msacm32/internal.c
index cfc4708fe46..cf76a574ab6 100644
--- a/dlls/msacm32/internal.c
+++ b/dlls/msacm32/internal.c
@@ -44,7 +44,7 @@ WINE_DEFAULT_DEBUG_CHANNEL(msacm);
 
 HANDLE MSACM_hHeap = NULL;
 PWINE_ACMDRIVERID MSACM_pFirstACMDriverID = NULL;
-PWINE_ACMDRIVERID MSACM_pLastACMDriverID = NULL;
+static PWINE_ACMDRIVERID MSACM_pLastACMDriverID;
 
 static DWORD MSACM_suspendBroadcastCount = 0;
 static BOOL MSACM_pendingBroadcast = FALSE;
diff --git a/dlls/msacm32/wineacm.h b/dlls/msacm32/wineacm.h
index 3c18a57b95a..3c001309d2a 100644
--- a/dlls/msacm32/wineacm.h
+++ b/dlls/msacm32/wineacm.h
@@ -370,7 +370,6 @@ typedef struct _WINE_ACMNOTIFYWND
 /* From internal.c */
 extern HANDLE MSACM_hHeap;
 extern PWINE_ACMDRIVERID MSACM_pFirstACMDriverID;
-extern PWINE_ACMDRIVERID MSACM_pLastACMDriverID;
 extern PWINE_ACMDRIVERID MSACM_RegisterDriver(LPCWSTR pszDriverAlias, LPCWSTR pszFileName,
 					      PWINE_ACMLOCALDRIVER pLocalDriver);
 extern void MSACM_RegisterAllDrivers(void);