diff --git a/dlls/snmpapi/main.c b/dlls/snmpapi/main.c
index 29c381c532d..b929ca3de82 100644
--- a/dlls/snmpapi/main.c
+++ b/dlls/snmpapi/main.c
@@ -144,7 +144,7 @@ BOOL WINAPI DllMain(
  *  probably ignored by Microsoft's compiler in this case. So declare it
  *  correctly in Wine so it works with all compilers.
  */
-void WINAPIV SnmpUtilDbgPrint(INT loglevel, LPSTR format, ...)
+VOID WINAPIV SnmpUtilDbgPrint(INT loglevel, LPSTR format, ...)
 {
     FIXME("(%d, %s)\n", loglevel, debugstr_a(format));
 }
@@ -170,7 +170,7 @@ LPVOID WINAPI SnmpUtilMemReAlloc(LPVOID mem, UINT nbytes)
 /***********************************************************************
  *      SnmpUtilMemFree         (SNMPAPI.@)
  */
-void WINAPI SnmpUtilMemFree(LPVOID mem)
+VOID WINAPI SnmpUtilMemFree(LPVOID mem)
 {
     TRACE("(%p)\n", mem);
     HeapFree(GetProcessHeap(), 0, mem);
@@ -188,7 +188,7 @@ INT WINAPI SnmpUtilAsnAnyCpy(AsnAny *dst, AsnAny *src)
 /***********************************************************************
  *      SnmpUtilAsnAnyFree      (SNMPAPI.@)
  */
-void WINAPI SnmpUtilAsnAnyFree(AsnAny *any)
+VOID WINAPI SnmpUtilAsnAnyFree(AsnAny *any)
 {
     TRACE("(%p)\n", any);
     asn_any_free(any);
@@ -224,7 +224,7 @@ INT WINAPI SnmpUtilOctetsCpy(AsnOctetString *dst, AsnOctetString *src)
 /***********************************************************************
  *      SnmpUtilOctetsFree      (SNMPAPI.@)
  */
-void WINAPI SnmpUtilOctetsFree(AsnOctetString *octets)
+VOID WINAPI SnmpUtilOctetsFree(AsnOctetString *octets)
 {
     TRACE("(%p)\n", octets);
 
@@ -326,7 +326,7 @@ INT WINAPI SnmpUtilOidCpy(AsnObjectIdentifier *dst, AsnObjectIdentifier *src)
 /***********************************************************************
  *      SnmpUtilOidFree         (SNMPAPI.@)
  */
-void WINAPI SnmpUtilOidFree(AsnObjectIdentifier *oid)
+VOID WINAPI SnmpUtilOidFree(AsnObjectIdentifier *oid)
 {
     TRACE("(%p)\n", oid);
 
@@ -402,7 +402,7 @@ INT WINAPI SnmpUtilVarBindCpy(SnmpVarBind *dst, SnmpVarBind *src)
 /***********************************************************************
  *      SnmpUtilVarBindFree     (SNMPAPI.@)
  */
-void WINAPI SnmpUtilVarBindFree(SnmpVarBind *vb)
+VOID WINAPI SnmpUtilVarBindFree(SnmpVarBind *vb)
 {
     TRACE("(%p)\n", vb);
 
@@ -459,7 +459,7 @@ INT WINAPI SnmpUtilVarBindListCpy(SnmpVarBindList *dst, SnmpVarBindList *src)
 /***********************************************************************
  *      SnmpUtilVarBindListFree (SNMPAPI.@)
  */
-void WINAPI SnmpUtilVarBindListFree(SnmpVarBindList *vb)
+VOID WINAPI SnmpUtilVarBindListFree(SnmpVarBindList *vb)
 {
     unsigned int i;
     SnmpVarBind *entry;
@@ -528,7 +528,7 @@ LPSTR WINAPI SnmpUtilOidToA(AsnObjectIdentifier *oid)
 /***********************************************************************
  *      SnmpUtilPrintOid        (SNMPAPI.@)
  */
-void WINAPI SnmpUtilPrintOid(AsnObjectIdentifier *oid)
+VOID WINAPI SnmpUtilPrintOid(AsnObjectIdentifier *oid)
 {
     unsigned int i;
 
@@ -547,7 +547,7 @@ void WINAPI SnmpUtilPrintOid(AsnObjectIdentifier *oid)
 /***********************************************************************
  *      SnmpUtilPrintAsnAny     (SNMPAPI.@)
  */
-void WINAPI SnmpUtilPrintAsnAny(AsnAny *any)
+VOID WINAPI SnmpUtilPrintAsnAny(AsnAny *any)
 {
     unsigned int i;
 
diff --git a/include/snmp.h b/include/snmp.h
index 2399d007a90..b41243bd1b6 100644
--- a/include/snmp.h
+++ b/include/snmp.h
@@ -224,7 +224,7 @@ BOOL WINAPI SnmpExtensionTrap(AsnObjectIdentifier *pEnterpriseOid,
  AsnInteger32 *pGenericTrapId, AsnInteger32 *pSpecificTrapId,
  AsnTimeticks *pTimeStamp, SnmpVarBindList *pVarBindList);
 
-void WINAPI SnmpExtensionClose(void);
+VOID WINAPI SnmpExtensionClose(VOID);
 
 typedef BOOL (WINAPI *PFNSNMPEXTENSIONINIT)(DWORD dwUptimeReference,
  HANDLE *phSubagentTrapEvent, AsnObjectIdentifier *pFirstSupportedRegion);
@@ -245,51 +245,51 @@ typedef BOOL (WINAPI *PFNSNMPEXTENSIONTRAP)(AsnObjectIdentifier *pEnterpriseOid,
  AsnInteger32 *pGenericTrapId, AsnInteger32 *pSpecificTrapId,
  AsnTimeticks *pTimeStamp, SnmpVarBindList *pVarBindList);
 
-typedef void (WINAPI *PFNSNMPEXTENSIONCLOSE)(void);
+typedef VOID (WINAPI *PFNSNMPEXTENSIONCLOSE)(VOID);
 
-int WINAPI SnmpUtilOidCpy(AsnObjectIdentifier *pOidDst,
+INT WINAPI SnmpUtilOidCpy(AsnObjectIdentifier *pOidDst,
  AsnObjectIdentifier *pOidSrc);
-int WINAPI SnmpUtilOidAppend(AsnObjectIdentifier *pOidDst,
+INT WINAPI SnmpUtilOidAppend(AsnObjectIdentifier *pOidDst,
  AsnObjectIdentifier *pOidSrc);
-int WINAPI SnmpUtilOidCmp(AsnObjectIdentifier *pOid1,
+INT WINAPI SnmpUtilOidCmp(AsnObjectIdentifier *pOid1,
  AsnObjectIdentifier *pOid2);
-int WINAPI SnmpUtilOidNCmp(AsnObjectIdentifier *pOid1,
+INT WINAPI SnmpUtilOidNCmp(AsnObjectIdentifier *pOid1,
  AsnObjectIdentifier *pOid2, UINT nSubIds);
-void WINAPI SnmpUtilOidFree(AsnObjectIdentifier *pOid);
+VOID WINAPI SnmpUtilOidFree(AsnObjectIdentifier *pOid);
 
-int WINAPI SnmpUtilOctetsCmp(AsnOctetString *pOctets1,
+INT WINAPI SnmpUtilOctetsCmp(AsnOctetString *pOctets1,
  AsnOctetString *pOctets2);
-int WINAPI SnmpUtilOctetsNCmp(AsnOctetString *pOctets1,
+INT WINAPI SnmpUtilOctetsNCmp(AsnOctetString *pOctets1,
  AsnOctetString *pOctets2, UINT nChars);
-int WINAPI SnmpUtilOctetsCpy(AsnOctetString *pOctetsDst,
+INT WINAPI SnmpUtilOctetsCpy(AsnOctetString *pOctetsDst,
  AsnOctetString *pOctetsSrc);
-void WINAPI SnmpUtilOctetsFree(AsnOctetString *pOctets);
+VOID WINAPI SnmpUtilOctetsFree(AsnOctetString *pOctets);
 
-int WINAPI SnmpUtilAsnAnyCpy(AsnAny *pAnyDst, AsnAny *pAnySrc);
-void WINAPI SnmpUtilAsnAnyFree(AsnAny *pAny);
+INT WINAPI SnmpUtilAsnAnyCpy(AsnAny *pAnyDst, AsnAny *pAnySrc);
+VOID WINAPI SnmpUtilAsnAnyFree(AsnAny *pAny);
 
-int WINAPI SnmpUtilVarBindCpy(SnmpVarBind *pVbDst, SnmpVarBind *pVbSrc);
-void WINAPI SnmpUtilVarBindFree(SnmpVarBind *pVb);
+INT WINAPI SnmpUtilVarBindCpy(SnmpVarBind *pVbDst, SnmpVarBind *pVbSrc);
+VOID WINAPI SnmpUtilVarBindFree(SnmpVarBind *pVb);
 
-int WINAPI SnmpUtilVarBindListCpy(SnmpVarBindList *pVblDst,
+INT WINAPI SnmpUtilVarBindListCpy(SnmpVarBindList *pVblDst,
  SnmpVarBindList *pVblSrc);
-void WINAPI SnmpUtilVarBindListFree(SnmpVarBindList *pVbl);
+VOID WINAPI SnmpUtilVarBindListFree(SnmpVarBindList *pVbl);
 
 LPVOID WINAPI SnmpUtilMemAlloc(UINT nBytes);
 LPVOID WINAPI SnmpUtilMemReAlloc(LPVOID pMem, UINT nBytes);
-void WINAPI SnmpUtilMemFree(LPVOID pMem);
+VOID WINAPI SnmpUtilMemFree(LPVOID pMem);
 
 LPSTR WINAPI SnmpUtilOidToA(AsnObjectIdentifier *Oid);
 LPSTR WINAPI SnmpUtilIdsToA(UINT *Ids, UINT IdLength);
 
-void WINAPI SnmpUtilPrintOid(AsnObjectIdentifier *Oid);
-void WINAPI SnmpUtilPrintAsnAny(AsnAny *pAny);
+VOID WINAPI SnmpUtilPrintOid(AsnObjectIdentifier *Oid);
+VOID WINAPI SnmpUtilPrintAsnAny(AsnAny *pAny);
 
-DWORD WINAPI SnmpSvcGetUptime(void);
-void WINAPI SnmpSvcSetLogLevel(int nLogLevel);
-void WINAPI SnmpSvcSetLogType(int nLogType);
+DWORD WINAPI SnmpSvcGetUptime(VOID);
+VOID WINAPI SnmpSvcSetLogLevel(INT nLogLevel);
+VOID WINAPI SnmpSvcSetLogType(INT nLogType);
 
-void WINAPIV SnmpUtilDbgPrint(int nLogLevel, LPSTR szFormat, ...);
+VOID WINAPIV SnmpUtilDbgPrint(INT nLogLevel, LPSTR szFormat, ...);
 
 #ifdef __cplusplus
 }
diff --git a/tools/winapi/win32.api b/tools/winapi/win32.api
index 65a8aff04a6..a130b0d5856 100644
--- a/tools/winapi/win32.api
+++ b/tools/winapi/win32.api
@@ -4153,6 +4153,31 @@ void
 LPCWSTR
 LPWSTR
 
+%%snmpapi.dll
+
+%void
+
+VOID
+
+%long
+
+INT
+UINT
+
+%str
+
+LPSTR
+
+%ptr
+
+AsnAny *
+AsnObjectIdentifier *
+AsnOctetString *
+LPVOID
+SnmpVarBind *
+SnmpVarBindList *
+UINT *
+
 %%sti.dll
 
 %long