diff --git a/dlls/api-ms-win-core-processthreads-l1-1-0/api-ms-win-core-processthreads-l1-1-0.spec b/dlls/api-ms-win-core-processthreads-l1-1-0/api-ms-win-core-processthreads-l1-1-0.spec
index ff13d484f67..154c875f814 100644
--- a/dlls/api-ms-win-core-processthreads-l1-1-0/api-ms-win-core-processthreads-l1-1-0.spec
+++ b/dlls/api-ms-win-core-processthreads-l1-1-0/api-ms-win-core-processthreads-l1-1-0.spec
@@ -32,7 +32,7 @@
 @ stdcall QueueUserAPC(ptr long long) kernel32.QueueUserAPC
 @ stdcall ResumeThread(long) kernel32.ResumeThread
 @ stdcall SetPriorityClass(long long) kernel32.SetPriorityClass
-@ stub SetProcessAffinityUpdateMode
+@ stdcall SetProcessAffinityUpdateMode(long long) kernel32.SetProcessAffinityUpdateMode
 @ stdcall SetProcessShutdownParameters(long long) kernel32.SetProcessShutdownParameters
 @ stdcall SetThreadPriority(long long) kernel32.SetThreadPriority
 @ stdcall SetThreadPriorityBoost(long long) kernel32.SetThreadPriorityBoost
diff --git a/dlls/api-ms-win-core-processthreads-l1-1-1/api-ms-win-core-processthreads-l1-1-1.spec b/dlls/api-ms-win-core-processthreads-l1-1-1/api-ms-win-core-processthreads-l1-1-1.spec
index 381db8aa6ea..ebbe55fe689 100644
--- a/dlls/api-ms-win-core-processthreads-l1-1-1/api-ms-win-core-processthreads-l1-1-1.spec
+++ b/dlls/api-ms-win-core-processthreads-l1-1-1/api-ms-win-core-processthreads-l1-1-1.spec
@@ -43,7 +43,7 @@
 @ stdcall QueueUserAPC(ptr long long) kernel32.QueueUserAPC
 @ stdcall ResumeThread(long) kernel32.ResumeThread
 @ stdcall SetPriorityClass(long long) kernel32.SetPriorityClass
-@ stub SetProcessAffinityUpdateMode
+@ stdcall SetProcessAffinityUpdateMode(long long) kernel32.SetProcessAffinityUpdateMode
 @ stub SetProcessMitigationPolicy
 @ stdcall SetProcessShutdownParameters(long long) kernel32.SetProcessShutdownParameters
 @ stdcall SetThreadContext(long ptr) kernel32.SetThreadContext
diff --git a/dlls/api-ms-win-core-processthreads-l1-1-2/api-ms-win-core-processthreads-l1-1-2.spec b/dlls/api-ms-win-core-processthreads-l1-1-2/api-ms-win-core-processthreads-l1-1-2.spec
index fc2feecdb01..db94c2e5e7f 100644
--- a/dlls/api-ms-win-core-processthreads-l1-1-2/api-ms-win-core-processthreads-l1-1-2.spec
+++ b/dlls/api-ms-win-core-processthreads-l1-1-2/api-ms-win-core-processthreads-l1-1-2.spec
@@ -48,7 +48,7 @@
 @ stdcall QueueUserAPC(ptr long long) kernel32.QueueUserAPC
 @ stdcall ResumeThread(long) kernel32.ResumeThread
 @ stdcall SetPriorityClass(long long) kernel32.SetPriorityClass
-@ stub SetProcessAffinityUpdateMode
+@ stdcall SetProcessAffinityUpdateMode(long long) kernel32.SetProcessAffinityUpdateMode
 @ stub SetProcessMitigationPolicy
 @ stdcall SetProcessPriorityBoost(long long) kernel32.SetProcessPriorityBoost
 @ stdcall SetProcessShutdownParameters(long long) kernel32.SetProcessShutdownParameters
diff --git a/dlls/kernel32/kernel32.spec b/dlls/kernel32/kernel32.spec
index e78c1ca8ab7..9ed5dfbccfa 100644
--- a/dlls/kernel32/kernel32.spec
+++ b/dlls/kernel32/kernel32.spec
@@ -1425,7 +1425,7 @@
 @ stdcall SetNamedPipeHandleState(long ptr ptr ptr)
 @ stdcall SetPriorityClass(long long)
 @ stdcall SetProcessAffinityMask(long long)
-# @ stub SetProcessAffinityUpdateMode
+@ stdcall SetProcessAffinityUpdateMode(long long)
 @ stdcall SetProcessDEPPolicy(long)
 # @ stub SetProcessPreferredUILanguages
 @ stdcall SetProcessPriorityBoost(long long)
diff --git a/dlls/kernel32/process.c b/dlls/kernel32/process.c
index df3426b30b0..ff56e9a692e 100644
--- a/dlls/kernel32/process.c
+++ b/dlls/kernel32/process.c
@@ -3324,6 +3324,17 @@ BOOL WINAPI GetProcessAffinityMask( HANDLE hProcess, PDWORD_PTR process_mask, PD
 }
 
 
+/***********************************************************************
+ *           SetProcessAffinityUpdateMode (KERNEL32.@)
+ */
+BOOL WINAPI SetProcessAffinityUpdateMode( HANDLE process, DWORD flags )
+{
+    FIXME("(%p,0x%08x): stub\n", process, flags);
+    SetLastError(ERROR_CALL_NOT_IMPLEMENTED);
+    return FALSE;
+}
+
+
 /***********************************************************************
  *           GetProcessVersion    (KERNEL32.@)
  */
diff --git a/dlls/kernelbase/kernelbase.spec b/dlls/kernelbase/kernelbase.spec
index 8cac67f0db1..fb7fafe47bb 100644
--- a/dlls/kernelbase/kernelbase.spec
+++ b/dlls/kernelbase/kernelbase.spec
@@ -1452,7 +1452,7 @@
 @ stdcall SetPriorityClass(long long) kernel32.SetPriorityClass
 @ stdcall SetPrivateObjectSecurity(long ptr ptr ptr long) advapi32.SetPrivateObjectSecurity
 @ stub SetPrivateObjectSecurityEx
-@ stub SetProcessAffinityUpdateMode
+@ stdcall SetProcessAffinityUpdateMode(long long) kernel32.SetProcessAffinityUpdateMode
 # @ stub SetProcessDefaultCpuSets
 # @ stub SetProcessGroupAffinity
 # @ stub SetProcessInformation