diff --git a/dlls/ole32/compobj.c b/dlls/ole32/compobj.c
index 0208bc5c979..7ce8a698e40 100644
--- a/dlls/ole32/compobj.c
+++ b/dlls/ole32/compobj.c
@@ -2347,7 +2347,7 @@ HRESULT WINAPI CoFileTimeNow( FILETIME *lpFileTime )
     return S_OK;
 }
 
-static void COM_RevokeAllClasses()
+static void COM_RevokeAllClasses(void)
 {
   EnterCriticalSection( &csRegisteredClassList );
 
diff --git a/dlls/ole32/git.c b/dlls/ole32/git.c
index a56e1d4e9d9..c750287aa85 100644
--- a/dlls/ole32/git.c
+++ b/dlls/ole32/git.c
@@ -391,7 +391,7 @@ static const IGlobalInterfaceTableVtbl StdGlobalInterfaceTableImpl_Vtbl =
 };
 
 /** This function constructs the GIT. It should only be called once **/
-void* StdGlobalInterfaceTable_Construct()
+void* StdGlobalInterfaceTable_Construct(void)
 {
   StdGlobalInterfaceTableImpl* newGIT;
 
diff --git a/dlls/ole32/ole2.c b/dlls/ole32/ole2.c
index bf6847c37a8..164970d4495 100644
--- a/dlls/ole32/ole2.c
+++ b/dlls/ole32/ole2.c
@@ -1814,7 +1814,7 @@ void WINAPI ReleaseStgMedium(
  *
  * Initializes the OLE drag and drop data structures.
  */
-static void OLEDD_Initialize()
+static void OLEDD_Initialize(void)
 {
     WNDCLASSA wndClass;
 
@@ -2160,7 +2160,7 @@ static void OLEDD_TrackStateChange(TrackerWindowInfo* trackerInfo)
  * a button state mask equivalent to the one passed in the
  * WM_MOUSEMOVE wParam.
  */
-static DWORD OLEDD_GetButtonState()
+static DWORD OLEDD_GetButtonState(void)
 {
   BYTE  keyboardState[256];
   DWORD keyMask = 0;
diff --git a/dlls/ole32/regsvr.c b/dlls/ole32/regsvr.c
index fad8f8ae860..b127c0d0277 100644
--- a/dlls/ole32/regsvr.c
+++ b/dlls/ole32/regsvr.c
@@ -636,7 +636,7 @@ static const struct regsvr_interface interface_list[] = {
 /***********************************************************************
  *		DllRegisterServer (OLE32.@)
  */
-HRESULT WINAPI DllRegisterServer()
+HRESULT WINAPI DllRegisterServer(void)
 {
     HRESULT hr;
 
@@ -651,7 +651,7 @@ HRESULT WINAPI DllRegisterServer()
 /***********************************************************************
  *		DllUnregisterServer (OLE32.@)
  */
-HRESULT WINAPI DllUnregisterServer()
+HRESULT WINAPI DllUnregisterServer(void)
 {
     HRESULT hr;
 
diff --git a/dlls/ole32/stubmanager.c b/dlls/ole32/stubmanager.c
index e0b0007c9a3..f187404eea1 100644
--- a/dlls/ole32/stubmanager.c
+++ b/dlls/ole32/stubmanager.c
@@ -739,7 +739,7 @@ static const IRemUnknownVtbl RemUnknown_Vtbl =
 };
 
 /* starts the IRemUnknown listener for the current apartment */
-HRESULT start_apartment_remote_unknown()
+HRESULT start_apartment_remote_unknown(void)
 {
     IRemUnknown *pRemUnknown;
     HRESULT hr = S_OK;