diff --git a/dlls/comctl32/tests/imagelist.c b/dlls/comctl32/tests/imagelist.c
index c23eee8b93c..4c7fb0e1c4f 100644
--- a/dlls/comctl32/tests/imagelist.c
+++ b/dlls/comctl32/tests/imagelist.c
@@ -81,7 +81,7 @@ static const BYTE bitmap_bits[48*48/8] =
   ROW48(0,0,0,0,0,0,0,0,0,0,0,0)
 };
 
-static HIMAGELIST createImageList(cx, cy)
+static HIMAGELIST createImageList(int cx, int cy)
 {
     /* Create an ImageList and put an image into it */
     HIMAGELIST himl = ImageList_Create(cx, cy, ILC_COLOR, 1, 1);
diff --git a/dlls/devenum/createdevenum.c b/dlls/devenum/createdevenum.c
index 1129adcf8b0..67a84696a40 100644
--- a/dlls/devenum/createdevenum.c
+++ b/dlls/devenum/createdevenum.c
@@ -44,7 +44,7 @@ static const WCHAR wszActiveMovieKey[] = {'S','o','f','t','w','a','r','e','\\',
                                    'd','e','v','e','n','u','m','\\',0};
 
 static ULONG WINAPI DEVENUM_ICreateDevEnum_AddRef(ICreateDevEnum * iface);
-static HRESULT DEVENUM_CreateSpecialCategories();
+static HRESULT DEVENUM_CreateSpecialCategories(void);
 
 /**********************************************************************
  * DEVENUM_ICreateDevEnum_QueryInterface (also IUnknown)
diff --git a/dlls/devenum/devenum_private.h b/dlls/devenum/devenum_private.h
index 596beb8da82..b48b3cbb94c 100644
--- a/dlls/devenum/devenum_private.h
+++ b/dlls/devenum/devenum_private.h
@@ -81,7 +81,7 @@ typedef struct
     HKEY hkey;
 } MediaCatMoniker;
 
-MediaCatMoniker * DEVENUM_IMediaCatMoniker_Construct();
+MediaCatMoniker * DEVENUM_IMediaCatMoniker_Construct(void);
 HRESULT DEVENUM_IEnumMoniker_Construct(HKEY hkey, IEnumMoniker ** ppEnumMoniker);
 HRESULT WINAPI DEVENUM_ICreateDevEnum_CreateClassEnumerator(
     ICreateDevEnum * iface,
diff --git a/dlls/dsound/tests/dsound_test.h b/dlls/dsound/tests/dsound_test.h
index 33e04f4669a..88f319d5d16 100644
--- a/dlls/dsound/tests/dsound_test.h
+++ b/dlls/dsound/tests/dsound_test.h
@@ -52,7 +52,7 @@ static const unsigned int formats[][4]={
 
 
 extern char* wave_generate_la(WAVEFORMATEX*,double,DWORD*);
-extern HWND get_hwnd();
+extern HWND get_hwnd(void);
 extern void init_format(WAVEFORMATEX*,int,int,int,int);
 extern void test_buffer(LPDIRECTSOUND,LPDIRECTSOUNDBUFFER,
                         BOOL,BOOL,LONG,BOOL,LONG,BOOL,double,BOOL,
diff --git a/dlls/glu32/glu.c b/dlls/glu32/glu.c
index 2971ad54e8e..697cb6a5dc1 100644
--- a/dlls/glu32/glu.c
+++ b/dlls/glu32/glu.c
@@ -146,8 +146,8 @@ int WINAPI wine_gluBuild2DMipmaps(int arg0,int arg1,int arg2,int arg3,int arg4,i
 /***********************************************************************
  *		gluNewQuadric (GLU32.@)
  */
-extern int gluNewQuadric();
-int WINAPI wine_gluNewQuadric() {
+extern int gluNewQuadric(void);
+int WINAPI wine_gluNewQuadric(void) {
 	return gluNewQuadric();
 }
 
@@ -234,8 +234,8 @@ int WINAPI wine_gluPartialDisk(void *arg0,double arg1,double arg2,int arg3,int a
 /***********************************************************************
  *		gluNewNurbsRenderer (GLU32.@)
  */
-extern int gluNewNurbsRenderer();
-int WINAPI wine_gluNewNurbsRenderer() {
+extern int gluNewNurbsRenderer(void);
+int WINAPI wine_gluNewNurbsRenderer(void) {
 	return gluNewNurbsRenderer();
 }
 
diff --git a/dlls/kernel/tests/pipe.c b/dlls/kernel/tests/pipe.c
index eb75ec4b63e..7bf82ddbc46 100644
--- a/dlls/kernel/tests/pipe.c
+++ b/dlls/kernel/tests/pipe.c
@@ -54,7 +54,7 @@
 
 static HANDLE alarm_event;
 
-static void test_CreateNamedPipe(pipemode)
+static void test_CreateNamedPipe(int pipemode)
 {
     HANDLE hnp;
     HANDLE hFile;
diff --git a/dlls/kernel/tests/thread.c b/dlls/kernel/tests/thread.c
index aa578fff9e7..d9822fd18d5 100644
--- a/dlls/kernel/tests/thread.c
+++ b/dlls/kernel/tests/thread.c
@@ -155,7 +155,7 @@ DWORD WINAPI threadFunc5(LPVOID p)
 #endif
 
 /* Check basic funcationality of CreateThread and Tls* functions */
-VOID test_CreateThread_basic()
+VOID test_CreateThread_basic(void)
 {
    HANDLE thread[NUM_THREADS],event[NUM_THREADS];
    DWORD threadid[NUM_THREADS],curthreadId;
@@ -217,7 +217,7 @@ VOID test_CreateThread_basic()
 }
 
 /* Check that using the CREATE_SUSPENDED flag works */
-VOID test_CreateThread_suspended()
+VOID test_CreateThread_suspended(void)
 {
   HANDLE thread;
   DWORD threadId;
@@ -246,7 +246,7 @@ VOID test_CreateThread_suspended()
 }
 
 /* Check that SuspendThread and ResumeThread work */
-VOID test_SuspendThread()
+VOID test_SuspendThread(void)
 {
   HANDLE thread,access_thread;
   DWORD threadId,exitCode,error;
@@ -303,12 +303,10 @@ VOID test_SuspendThread()
 
 /* Check that TerminateThread works properly
 */
-VOID test_TerminateThread()
+VOID test_TerminateThread(void)
 {
   HANDLE thread,access_thread,event;
   DWORD threadId,exitCode;
-  int i,error;
-  i=0; error=0;
   event=CreateEventA(NULL,TRUE,FALSE,NULL);
   thread = CreateThread(NULL,0,threadFunc4,
                         (LPVOID)event, 0,&threadId);
@@ -344,7 +342,7 @@ VOID test_TerminateThread()
 /* Check if CreateThread obeys the specified stack size.  This code does
    not work properly, and is currently disabled
 */
-VOID test_CreateThread_stack()
+VOID test_CreateThread_stack(void)
 {
 #if CHECK_STACK
 /* The only way I know of to test the stack size is to use alloca
@@ -371,7 +369,7 @@ VOID test_CreateThread_stack()
 }
 
 /* Check whether setting/retrieving thread priorities works */
-VOID test_thread_priority()
+VOID test_thread_priority(void)
 {
    HANDLE curthread,access_thread;
    DWORD curthreadId,exitCode;
@@ -457,7 +455,7 @@ VOID test_thread_priority()
 }
 
 /* check the GetThreadTimes function */
-VOID test_GetThreadTimes()
+VOID test_GetThreadTimes(void)
 {
      HANDLE thread,access_thread=NULL;
      FILETIME creationTime,exitTime,kernelTime,userTime;
@@ -508,7 +506,7 @@ VOID test_GetThreadTimes()
 /* Check the processor affinity functions */
 /* NOTE: These functions should also be checked that they obey access control
 */
-VOID test_thread_processor()
+VOID test_thread_processor(void)
 {
    HANDLE curthread,curproc;
    DWORD processMask,systemMask;
diff --git a/dlls/msacm/wineacm.h b/dlls/msacm/wineacm.h
index 4f781b41d43..c844ab51c22 100644
--- a/dlls/msacm/wineacm.h
+++ b/dlls/msacm/wineacm.h
@@ -184,8 +184,7 @@ typedef BOOL16 (CALLBACK *ACMFORMATTAGENUMCB16)(
  * Functions - Win16
  */
 
-DWORD WINAPI acmGetVersion16(
-);
+DWORD WINAPI acmGetVersion16(void);
 MMRESULT16 WINAPI acmMetrics16(
   HACMOBJ16 hao, UINT16 uMetric, LPVOID pMetric
 );
diff --git a/dlls/msi/sql.y b/dlls/msi/sql.y
index 18600edb49d..cb06805f049 100644
--- a/dlls/msi/sql.y
+++ b/dlls/msi/sql.y
@@ -64,7 +64,7 @@ static struct expr * EXPR_complex( struct expr *l, UINT op, struct expr *r );
 static struct expr * EXPR_column( LPWSTR );
 static struct expr * EXPR_ival( struct sql_str *);
 static struct expr * EXPR_sval( struct sql_str *);
-static struct expr * EXPR_wildcard();
+static struct expr * EXPR_wildcard(void);
 
 %}
 
diff --git a/dlls/msvcrt/msvcrt.h b/dlls/msvcrt/msvcrt.h
index b455a6eedbf..fe72cae94f0 100644
--- a/dlls/msvcrt/msvcrt.h
+++ b/dlls/msvcrt/msvcrt.h
@@ -560,13 +560,13 @@ int            MSVCRT_ungetc(int,MSVCRT_FILE*);
 MSVCRT_wint_t  MSVCRT_fgetwc(MSVCRT_FILE*);
 MSVCRT_wint_t  MSVCRT_ungetwc(MSVCRT_wint_t,MSVCRT_FILE*);
 void           MSVCRT__exit(int);
-void           MSVCRT_abort();
+void           MSVCRT_abort(void);
 unsigned long* MSVCRT___doserrno(void);
 int*           MSVCRT__errno(void);
 char*          MSVCRT_getenv(const char*);
 char*          MSVCRT_setlocale(int,const char*);
 int            MSVCRT_fclose(MSVCRT_FILE*);
-void           MSVCRT_terminate();
+void           MSVCRT_terminate(void);
 MSVCRT_FILE*   MSVCRT__p__iob(void);
 MSVCRT_time_t  MSVCRT_mktime(struct MSVCRT_tm *t);
 struct MSVCRT_tm* MSVCRT_localtime(const MSVCRT_time_t* secs);
diff --git a/dlls/ole32/compobj.c b/dlls/ole32/compobj.c
index 3d94fe846d3..ee46a33198b 100644
--- a/dlls/ole32/compobj.c
+++ b/dlls/ole32/compobj.c
@@ -64,8 +64,8 @@ typedef LPCSTR LPCOLESTR16;
 HINSTANCE       COMPOBJ_hInstance32 = 0;
 
 static HRESULT COM_GetRegisteredClassObject(REFCLSID rclsid, DWORD dwClsContext, LPUNKNOWN*  ppUnk);
-static void COM_RevokeAllClasses();
-static void COM_ExternalLockFreeList();
+static void COM_RevokeAllClasses(void);
+static void COM_ExternalLockFreeList(void);
 
 const CLSID CLSID_StdGlobalInterfaceTable = { 0x00000323, 0, 0, {0xc0, 0, 0, 0, 0, 0, 0, 0x46} };
 
diff --git a/dlls/ole32/compobj_private.h b/dlls/ole32/compobj_private.h
index fde38214d26..a3c987b9c08 100644
--- a/dlls/ole32/compobj_private.h
+++ b/dlls/ole32/compobj_private.h
@@ -109,7 +109,7 @@ typedef struct tagAPARTMENT {
 
 extern APARTMENT MTA, *apts;
 
-extern void* StdGlobalInterfaceTable_Construct();
+extern void* StdGlobalInterfaceTable_Construct(void);
 extern void  StdGlobalInterfaceTable_Destroy(void* self);
 extern HRESULT StdGlobalInterfaceTable_GetFactory(LPVOID *ppv);
 
@@ -148,19 +148,19 @@ MARSHAL_Compare_Mids_NoInterface(wine_marshal_id *mid1, wine_marshal_id *mid2) {
 
 HRESULT MARSHAL_Find_Stub_Buffer(wine_marshal_id *mid,IRpcStubBuffer **stub);
 void    MARSHAL_Invalidate_Stub_From_MID(wine_marshal_id *mid);
-HRESULT MARSHAL_Disconnect_Proxies();
+HRESULT MARSHAL_Disconnect_Proxies(void);
 
 HRESULT MARSHAL_GetStandardMarshalCF(LPVOID *ppv);
 
-void start_listener_thread();
+void start_listener_thread(void);
 
 extern HRESULT PIPE_GetNewPipeBuf(wine_marshal_id *mid, IRpcChannelBuffer **pipebuf);
 
 /* This function initialize the Running Object Table */
-HRESULT WINAPI RunningObjectTableImpl_Initialize();
+HRESULT WINAPI RunningObjectTableImpl_Initialize(void);
 
 /* This function uninitialize the Running Object Table */
-HRESULT WINAPI RunningObjectTableImpl_UnInitialize();
+HRESULT WINAPI RunningObjectTableImpl_UnInitialize(void);
 
 /* This function decomposes a String path to a String Table containing all the elements ("\" or "subDirectory" or "Directory" or "FileName") of the path */
 int WINAPI FileMonikerImpl_DecomposePath(LPCOLESTR str, LPOLESTR** stringTable);
diff --git a/dlls/ole32/ifs.h b/dlls/ole32/ifs.h
index f0252995b90..13080e3b0b8 100644
--- a/dlls/ole32/ifs.h
+++ b/dlls/ole32/ifs.h
@@ -54,7 +54,7 @@ DECLARE_INTERFACE_(IMalloc16,IUnknown)
 
 /**********************************************************************/
 
-extern LPMALLOC16 IMalloc16_Constructor();
+extern LPMALLOC16 IMalloc16_Constructor(void);
 
 /**********************************************************************/
 
diff --git a/dlls/ole32/moniker.c b/dlls/ole32/moniker.c
index 57f05740821..5485099751f 100644
--- a/dlls/ole32/moniker.c
+++ b/dlls/ole32/moniker.c
@@ -86,9 +86,9 @@ static HRESULT WINAPI RunningObjectTableImpl_NoteChangeTime(IRunningObjectTable*
 static HRESULT WINAPI RunningObjectTableImpl_GetTimeOfLastChange(IRunningObjectTable* iface, IMoniker* pmkObjectName,FILETIME* pfiletime);
 static HRESULT WINAPI RunningObjectTableImpl_EnumRunning(IRunningObjectTable* iface, IEnumMoniker** ppenumMoniker);
 /* Local functions*/
-HRESULT WINAPI RunningObjectTableImpl_Initialize();
-HRESULT WINAPI RunningObjectTableImpl_UnInitialize();
-HRESULT WINAPI RunningObjectTableImpl_Destroy();
+HRESULT WINAPI RunningObjectTableImpl_Initialize(void);
+HRESULT WINAPI RunningObjectTableImpl_UnInitialize(void);
+HRESULT WINAPI RunningObjectTableImpl_Destroy(void);
 HRESULT WINAPI RunningObjectTableImpl_GetObjectIndex(RunningObjectTableImpl* This,DWORD identReg,IMoniker* pmk,DWORD *indx);
 
 /* Virtual function table for the IRunningObjectTable class. */
diff --git a/dlls/ole32/ole2.c b/dlls/ole32/ole2.c
index 51a1d73e1e2..d869be7c443 100644
--- a/dlls/ole32/ole2.c
+++ b/dlls/ole32/ole2.c
@@ -129,8 +129,8 @@ static void OLEUTL_ReadRegistryDWORDValue(HKEY regKey, DWORD* pdwValue);
 /******************************************************************************
  * These are the prototypes of the utility methods used to manage a shared menu
  */
-static void OLEMenu_Initialize();
-static void OLEMenu_UnInitialize();
+static void OLEMenu_Initialize(void);
+static void OLEMenu_UnInitialize(void);
 BOOL OLEMenu_InstallHooks( DWORD tid );
 BOOL OLEMenu_UnInstallHooks( DWORD tid );
 OleMenuHookItem * OLEMenu_IsHookInstalled( DWORD tid );
@@ -142,14 +142,14 @@ LRESULT CALLBACK OLEMenu_GetMsgProc(INT code, WPARAM wParam, LPARAM lParam);
 /******************************************************************************
  * These are the prototypes of the OLE Clipboard initialization methods (in clipboard.c)
  */
-void OLEClipbrd_UnInitialize();
-void OLEClipbrd_Initialize();
+void OLEClipbrd_UnInitialize(void);
+void OLEClipbrd_Initialize(void);
 
 /******************************************************************************
  * These are the prototypes of the utility methods used for OLE Drag n Drop
  */
-static void            OLEDD_Initialize();
-static void            OLEDD_UnInitialize();
+static void            OLEDD_Initialize(void);
+static void            OLEDD_UnInitialize(void);
 static void            OLEDD_InsertDropTarget(
 			 DropTargetNode* nodeToAdd);
 static DropTargetNode* OLEDD_ExtractDropTarget(
@@ -169,7 +169,7 @@ static void OLEDD_TrackStateChange(
                          TrackerWindowInfo* trackerInfo,
 			 POINT            mousePos,
 			 DWORD              keyState);
-static DWORD OLEDD_GetButtonState();
+static DWORD OLEDD_GetButtonState(void);
 
 
 /******************************************************************************
diff --git a/dlls/ole32/oleobj.c b/dlls/ole32/oleobj.c
index bfda94b90cc..45efbc0c528 100644
--- a/dlls/ole32/oleobj.c
+++ b/dlls/ole32/oleobj.c
@@ -50,7 +50,7 @@ typedef struct OleAdviseHolderImpl
 
 } OleAdviseHolderImpl;
 
-static LPOLEADVISEHOLDER OleAdviseHolderImpl_Constructor();
+static LPOLEADVISEHOLDER OleAdviseHolderImpl_Constructor(void);
 static void              OleAdviseHolderImpl_Destructor(OleAdviseHolderImpl* ptrToDestroy);
 static HRESULT WINAPI    OleAdviseHolderImpl_QueryInterface(LPOLEADVISEHOLDER,REFIID,LPVOID*);
 static ULONG WINAPI      OleAdviseHolderImpl_AddRef(LPOLEADVISEHOLDER);
@@ -377,7 +377,7 @@ typedef struct DataAdviseHolder
 /**************************************************************************
  *  DataAdviseHolder method prototypes
  */
-static IDataAdviseHolder* DataAdviseHolder_Constructor();
+static IDataAdviseHolder* DataAdviseHolder_Constructor(void);
 static void               DataAdviseHolder_Destructor(DataAdviseHolder* ptrToDestroy);
 static HRESULT WINAPI     DataAdviseHolder_QueryInterface(
 			    IDataAdviseHolder*      iface,
diff --git a/dlls/oleaut32/typelib.c b/dlls/oleaut32/typelib.c
index d5edb41afac..9de40378efc 100644
--- a/dlls/oleaut32/typelib.c
+++ b/dlls/oleaut32/typelib.c
@@ -989,7 +989,7 @@ typedef struct tagITypeInfoImpl
 static struct ITypeInfo2Vtbl tinfvt;
 static struct ITypeCompVtbl  tcompvt;
 
-static ITypeInfo2 * WINAPI ITypeInfo_Constructor();
+static ITypeInfo2 * WINAPI ITypeInfo_Constructor(void);
 
 typedef struct tagTLBContext
 {
diff --git a/dlls/richedit/reader.c b/dlls/richedit/reader.c
index 84258439abc..5da908309eb 100644
--- a/dlls/richedit/reader.c
+++ b/dlls/richedit/reader.c
@@ -98,9 +98,9 @@ static void	ReadStyleSheet (RTF_Info *);
 static void	ReadInfoGroup (RTF_Info *);
 static void	ReadPictGroup (RTF_Info *);
 static void	ReadObjGroup (RTF_Info *);
-static void	LookupInit ();
+static void	LookupInit (void);
 static void	Lookup (RTF_Info *, char *);
-static int	Hash ();
+static int	Hash (char*);
 
 static void	CharSetInit (RTF_Info *);
 static void	ReadCharSetMaps (RTF_Info *);
@@ -2451,7 +2451,7 @@ static RTFKey	rtfKey[] =
  * Initialize lookup table hash values.  Only need to do this once.
  */
 
-static void LookupInit()
+static void LookupInit(void)
 {
 static int	inited = 0;
 RTFKey	*rp;
diff --git a/dlls/richedit/rtf2text.h b/dlls/richedit/rtf2text.h
index 67700b31c95..b897df25c85 100644
--- a/dlls/richedit/rtf2text.h
+++ b/dlls/richedit/rtf2text.h
@@ -1,2 +1,2 @@
-void	WriterInit ();
-int	BeginFile ();
+void	WriterInit (RTF_Info *);
+int	BeginFile (RTF_Info *);
diff --git a/dlls/shell32/undocshell.h b/dlls/shell32/undocshell.h
index a661da1f9d7..2ae56a8b3d8 100644
--- a/dlls/shell32/undocshell.h
+++ b/dlls/shell32/undocshell.h
@@ -559,7 +559,7 @@ HRESULT WINAPI SHCreateDefClassObject(
 	LPDWORD lpdwUsage,
 	REFIID riidObject);
 
-void WINAPI SHFreeUnusedLibraries();
+void WINAPI SHFreeUnusedLibraries(void);
 
 /* SHCreateLinks flags */
 #define SHCLF_PREFIXNAME       0x01
diff --git a/dlls/uxtheme/uxthemedll.h b/dlls/uxtheme/uxthemedll.h
index 4ac851d6314..cfd80fb016b 100644
--- a/dlls/uxtheme/uxthemedll.h
+++ b/dlls/uxtheme/uxthemedll.h
@@ -67,7 +67,7 @@ typedef BOOL (CALLBACK*ParseThemeIniFileProc)(DWORD dwType, LPWSTR pszParam1,
                                               DWORD dwParam, LPVOID lpData);
 
 /* Declarations for undocumented functions for use internally */
-DWORD WINAPI QueryThemeServices();
+DWORD WINAPI QueryThemeServices(void);
 HRESULT WINAPI OpenThemeFile(LPCWSTR pszThemeFileName, LPCWSTR pszColorName,
                              LPCWSTR pszSizeName, HTHEMEFILE *hThemeFile,
                              DWORD unknown);
diff --git a/dlls/winaspi/aspi.c b/dlls/winaspi/aspi.c
index e27c315dec2..d1fb0a0b8d0 100644
--- a/dlls/winaspi/aspi.c
+++ b/dlls/winaspi/aspi.c
@@ -65,11 +65,11 @@ WINE_DEFAULT_DEBUG_CHANNEL(aspi);
 
 /* Internal function prototypes */
 static void
-SCSI_GetProcinfo();
+SCSI_GetProcinfo(void);
 
 #ifdef linux
 static void
-SCSI_MapHCtoController();
+SCSI_MapHCtoController(void);
 #endif
 
 static void set_last_error(void)
diff --git a/dlls/winaspi/winescsi.h b/dlls/winaspi/winescsi.h
index 4b9dd7ac372..aeb12b007b3 100644
--- a/dlls/winaspi/winescsi.h
+++ b/dlls/winaspi/winescsi.h
@@ -58,10 +58,10 @@ struct sg_header
 
 /* Function prototypes from dlls/wnaspi32/aspi.c */
 void
-SCSI_Init();
+SCSI_Init(void);
 
 int
-ASPI_GetNumControllers();
+ASPI_GetNumControllers(void);
 
 int
 SCSI_OpenDevice( int h, int c, int t, int d );
diff --git a/dlls/winedos/vga.h b/dlls/winedos/vga.h
index f820c2479b0..f3d033fb3c8 100644
--- a/dlls/winedos/vga.h
+++ b/dlls/winedos/vga.h
@@ -39,7 +39,7 @@ void VGA_SetQuadPalette(RGBQUAD*color,int start,int len);
 LPSTR VGA_Lock(unsigned*Pitch,unsigned*Height,unsigned*Width,unsigned*Depth);
 void VGA_Unlock(void);
 void VGA_SetWindowStart(int start);
-int  VGA_GetWindowStart();
+int  VGA_GetWindowStart(void);
 void VGA_ShowMouse(BOOL show);
 
 /* text mode */
diff --git a/dlls/wininet/internet.c b/dlls/wininet/internet.c
index 40a759f75c0..9d60f1ab6de 100644
--- a/dlls/wininet/internet.c
+++ b/dlls/wininet/internet.c
@@ -88,7 +88,7 @@ static VOID INTERNET_CloseHandle(LPWININETHANDLEHEADER hdr);
 BOOL WINAPI INTERNET_FindNextFileW(LPWININETFINDNEXTW lpwh, LPVOID lpvFindData);
 HINTERNET WINAPI INTERNET_InternetOpenUrlW(LPWININETAPPINFOW hIC, LPCWSTR lpszUrl,
               LPCWSTR lpszHeaders, DWORD dwHeadersLength, DWORD dwFlags, DWORD dwContext);
-static VOID INTERNET_ExecuteWork();
+static VOID INTERNET_ExecuteWork(void);
 
 static DWORD g_dwTlsErrIndex = TLS_OUT_OF_INDEXES;
 static DWORD dwNumThreads;
@@ -102,8 +102,8 @@ static LPWORKREQUEST lpHeadWorkQueue;
 static LPWORKREQUEST lpWorkQueueTail;
 static HMODULE WININET_hModule;
 
-extern void URLCacheContainers_CreateDefaults();
-extern void URLCacheContainers_DeleteAll();
+extern void URLCacheContainers_CreateDefaults(void);
+extern void URLCacheContainers_DeleteAll(void);
 
 #define HANDLE_CHUNK_SIZE 0x10
 
diff --git a/dlls/wininet/internet.h b/dlls/wininet/internet.h
index f02c4ae21b9..f9c8bf199ed 100644
--- a/dlls/wininet/internet.h
+++ b/dlls/wininet/internet.h
@@ -412,9 +412,9 @@ BOOL GetAddress(LPCWSTR lpszServerName, INTERNET_PORT nServerPort,
 	struct hostent **phe, struct sockaddr_in *psa);
 
 void INTERNET_SetLastError(DWORD dwError);
-DWORD INTERNET_GetLastError();
+DWORD INTERNET_GetLastError(void);
 BOOL INTERNET_AsyncCall(LPWORKREQUEST lpWorkRequest);
-LPSTR INTERNET_GetResponseBuffer();
+LPSTR INTERNET_GetResponseBuffer(void);
 LPSTR INTERNET_GetNextLine(INT nSocket, LPDWORD dwLen);
 
 BOOLAPI FTP_FtpPutFileW(LPWININETFTPSESSIONW lpwfs, LPCWSTR lpszLocalFile,
diff --git a/dlls/winspool/wspool.c b/dlls/winspool/wspool.c
index f6cdb9cd12f..c8eebcb0201 100644
--- a/dlls/winspool/wspool.c
+++ b/dlls/winspool/wspool.c
@@ -43,7 +43,7 @@ BOOL WINAPI DllMain(HINSTANCE hInstance, DWORD reason, LPVOID lpReserved)
   switch (reason)
   {
     case DLL_PROCESS_ATTACH: {
-      extern void WINSPOOL_LoadSystemPrinters();
+      extern void WINSPOOL_LoadSystemPrinters(void);
 
       DisableThreadLibraryCalls(hInstance);
       WINSPOOL_LoadSystemPrinters();
diff --git a/include/imm.h b/include/imm.h
index 769d3f5ea3e..9ba4e9a797c 100644
--- a/include/imm.h
+++ b/include/imm.h
@@ -468,7 +468,7 @@ BOOL   WINAPI ImmAssociateContextEx(HWND, HIMC, DWORD);
 BOOL   WINAPI ImmConfigureIMEA(HKL, HWND, DWORD, LPVOID);
 BOOL   WINAPI ImmConfigureIMEW(HKL, HWND, DWORD, LPVOID);
 #define  ImmConfigureIME WINELIB_NAME_AW(ImmConfigureIME)
-HIMC   WINAPI ImmCreateContext();
+HIMC   WINAPI ImmCreateContext(void);
 BOOL   WINAPI ImmDestroyContext(HIMC hIMC);
 BOOL   WINAPI ImmDisableIME(DWORD idThread);
 UINT   WINAPI ImmEnumRegisterWordA(HKL, REGISTERWORDENUMPROCA, LPCSTR, DWORD, LPCSTR, LPVOID);
diff --git a/include/msi.h b/include/msi.h
index 5d9a17b5175..dc64fa832ff 100644
--- a/include/msi.h
+++ b/include/msi.h
@@ -254,7 +254,7 @@ UINT WINAPI MsiGetFileVersionW(LPCWSTR szFilePath, LPWSTR lpVersionBuf, DWORD* p
  * Non Unicode
  */
 UINT WINAPI MsiCloseHandle(MSIHANDLE);
-UINT WINAPI MsiCloseAllHandles();
+UINT WINAPI MsiCloseAllHandles(void);
 INSTALLUILEVEL WINAPI MsiSetInternalUI(INSTALLUILEVEL, HWND*);
 
 #ifdef __cplusplus
diff --git a/include/msvcrt/eh.h b/include/msvcrt/eh.h
index 162d2296f49..dce8c2d756f 100644
--- a/include/msvcrt/eh.h
+++ b/include/msvcrt/eh.h
@@ -29,17 +29,17 @@
 
 struct _EXCEPTION_POINTERS;
 
-typedef void (*terminate_handler)();
-typedef void (*terminate_function)();
-typedef void (*unexpected_handler)();
-typedef void (*unexpected_function)();
+typedef void (*terminate_handler)(void);
+typedef void (*terminate_function)(void);
+typedef void (*unexpected_handler)(void);
+typedef void (*unexpected_function)(void);
 typedef void (*_se_translator_function)(unsigned int code, struct _EXCEPTION_POINTERS *info);
 
 terminate_function set_terminate(terminate_function func);
 unexpected_function set_unexpected(unexpected_function func);
 _se_translator_function _set_se_translator(_se_translator_function func);
 
-void        terminate();
-void        unexpected();
+void        terminate(void);
+void        unexpected(void);
 
 #endif /* __WINE_EH_H */
diff --git a/include/msvcrt/stddef.h b/include/msvcrt/stddef.h
index 1eb1a6917db..6a689944c50 100644
--- a/include/msvcrt/stddef.h
+++ b/include/msvcrt/stddef.h
@@ -55,8 +55,8 @@ typedef unsigned int size_t;
 extern "C" {
 #endif
 
-unsigned long               __threadid();
-unsigned long               __threadhandle();
+unsigned long               __threadid(void);
+unsigned long               __threadhandle(void);
 #define _threadid          (__threadid())
 
 #ifdef __cplusplus
diff --git a/include/msvcrt/stdlib.h b/include/msvcrt/stdlib.h
index 35488d5b046..d90350042ce 100644
--- a/include/msvcrt/stdlib.h
+++ b/include/msvcrt/stdlib.h
@@ -78,10 +78,10 @@ typedef unsigned int size_t;
 extern "C" {
 #endif
 
-extern unsigned int*         __p__osver();
-extern unsigned int*         __p__winver();
-extern unsigned int*         __p__winmajor();
-extern unsigned int*         __p__winminor();
+extern unsigned int*         __p__osver(void);
+extern unsigned int*         __p__winver(void);
+extern unsigned int*         __p__winmajor(void);
+extern unsigned int*         __p__winminor(void);
 #define _osver             (*__p__osver())
 #define _winver            (*__p__winver())
 #define _winmajor          (*__p__winmajor())
@@ -145,7 +145,7 @@ char*       _ui64toa(unsigned __int64,char*,int);
 char*       _ultoa(unsigned long,char*,int);
 
 void        _exit(int);
-void        abort();
+void        abort(void);
 int         abs(int);
 int         atexit(void (*)(void));
 double      atof(const char*);
diff --git a/include/shlwapi.h b/include/shlwapi.h
index 932bb84f89b..65bf282b47f 100644
--- a/include/shlwapi.h
+++ b/include/shlwapi.h
@@ -946,7 +946,7 @@ HRESULT WINAPI SHAutoComplete(HWND,DWORD);
 /* Threads */
 HRESULT WINAPI SHGetThreadRef(IUnknown**);
 HRESULT WINAPI SHSetThreadRef(IUnknown*);
-HRESULT WINAPI SHReleaseThreadRef();
+HRESULT WINAPI SHReleaseThreadRef(void);
 
 /* SHCreateThread flags */
 #define CTF_INSIST          0x01 /* Always call */
diff --git a/include/uxtheme.h b/include/uxtheme.h
index 31b220ca1e0..47b14f1a5a3 100644
--- a/include/uxtheme.h
+++ b/include/uxtheme.h
@@ -66,7 +66,7 @@ HRESULT WINAPI GetCurrentThemeName(LPWSTR,int,LPWSTR,int,LPWSTR,int);
 #define STAP_ALLOW_CONTROLS     (1<<1)
 #define STAP_ALLOW_WEBCONTENT   (1<<2)
 
-DWORD WINAPI GetThemeAppProperties();
+DWORD WINAPI GetThemeAppProperties(void);
 HRESULT WINAPI GetThemeBackgroundContentRect(HTHEME,HDC,int,int,
                                              const RECT*,RECT*);
 HRESULT WINAPI GetThemeBackgroundExtent(HTHEME,HDC,int,int,const RECT*,RECT*);
@@ -162,10 +162,10 @@ HTHEME WINAPI GetWindowTheme(HWND);
 
 HRESULT WINAPI HitTestThemeBackground(HTHEME,HDC,int,int,DWORD,const RECT*,
                                       HRGN,POINT,WORD*);
-BOOL WINAPI IsAppThemed();
-BOOL WINAPI IsThemeActive();
+BOOL WINAPI IsAppThemed(void);
+BOOL WINAPI IsThemeActive(void);
 BOOL WINAPI IsThemeBackgroundPartiallyTransparent(HTHEME,int,int);
-BOOL WINAPI IsThemeDialogTextureEnabled();
+BOOL WINAPI IsThemeDialogTextureEnabled(void);
 BOOL WINAPI IsThemePartDefined(HTHEME,int,int);
 HTHEME WINAPI OpenThemeData(HWND,LPCWSTR);
 void WINAPI SetThemeAppProperties(DWORD);