diff --git a/include/winbase.h b/include/winbase.h
index c5332c09942..5d8b1ffcd04 100644
--- a/include/winbase.h
+++ b/include/winbase.h
@@ -2085,6 +2085,7 @@ WINBASEAPI BOOL        WINAPI GetLogicalProcessorInformation(PSYSTEM_LOGICAL_PRO
 WINBASEAPI BOOL        WINAPI GetLogicalProcessorInformationEx(LOGICAL_PROCESSOR_RELATIONSHIP,PSYSTEM_LOGICAL_PROCESSOR_INFORMATION_EX,PDWORD);
 WINBASEAPI DWORD       WINAPI GetProcessHeaps(DWORD,PHANDLE);
 WINBASEAPI DWORD       WINAPI GetProcessId(HANDLE);
+WINBASEAPI DWORD       WINAPI GetProcessIdOfThread(HANDLE);
 WINBASEAPI BOOL        WINAPI GetProcessIoCounters(HANDLE,PIO_COUNTERS);
 WINBASEAPI BOOL        WINAPI GetProcessPriorityBoost(HANDLE,PBOOL);
 WINBASEAPI BOOL        WINAPI GetProcessShutdownParameters(LPDWORD,LPDWORD);