diff --git a/dlls/ntoskrnl.exe/ntoskrnl.c b/dlls/ntoskrnl.exe/ntoskrnl.c
index f266dce9b90..c1e6a9cf026 100644
--- a/dlls/ntoskrnl.exe/ntoskrnl.c
+++ b/dlls/ntoskrnl.exe/ntoskrnl.c
@@ -2832,6 +2832,14 @@ PVOID WINAPI  MmMapLockedPagesSpecifyCache(PMDLX MemoryDescriptorList, KPROCESSO
     return NULL;
 }
 
+/***********************************************************************
+ *           MmUnmapLockedPages  (NTOSKRNL.EXE.@)
+ */
+void WINAPI MmUnmapLockedPages( void *base, MDL *mdl )
+{
+    FIXME( "(%p %p_\n", base, mdl );
+}
+
 /***********************************************************************
  *           MmUnlockPagableImageSection  (NTOSKRNL.EXE.@)
  */
diff --git a/dlls/ntoskrnl.exe/ntoskrnl.exe.spec b/dlls/ntoskrnl.exe/ntoskrnl.exe.spec
index f965ff55ecd..633a8c4b6c3 100644
--- a/dlls/ntoskrnl.exe/ntoskrnl.exe.spec
+++ b/dlls/ntoskrnl.exe/ntoskrnl.exe.spec
@@ -733,7 +733,7 @@
 @ stdcall MmUnlockPagableImageSection(ptr)
 @ stdcall MmUnlockPages(ptr)
 @ stdcall MmUnmapIoSpace(ptr long)
-@ stub MmUnmapLockedPages
+@ stdcall MmUnmapLockedPages(ptr ptr)
 @ stub MmUnmapReservedMapping
 @ stub MmUnmapVideoDisplay
 @ stub MmUnmapViewInSessionSpace
diff --git a/dlls/ntoskrnl.exe/tests/driver.c b/dlls/ntoskrnl.exe/tests/driver.c
index 5f65f6694a1..9b3a2193633 100644
--- a/dlls/ntoskrnl.exe/tests/driver.c
+++ b/dlls/ntoskrnl.exe/tests/driver.c
@@ -249,7 +249,7 @@ static void test_mdl_map(void)
 todo_wine
     ok(addr != NULL, "MmMapLockedPagesSpecifyCache failed\n");
 
-    /* MmUnmapLockedPages(addr, mdl); */
+    MmUnmapLockedPages(addr, mdl);
 
     IoFreeMdl(mdl);
 }
diff --git a/include/ddk/wdm.h b/include/ddk/wdm.h
index a66a5829776..57a53573f8b 100644
--- a/include/ddk/wdm.h
+++ b/include/ddk/wdm.h
@@ -1615,6 +1615,7 @@ void *    WINAPI MmGetSystemRoutineAddress(UNICODE_STRING*);
 PVOID     WINAPI MmMapLockedPagesSpecifyCache(PMDL,KPROCESSOR_MODE,MEMORY_CACHING_TYPE,PVOID,ULONG,ULONG);
 MM_SYSTEMSIZE WINAPI MmQuerySystemSize(void);
 void      WINAPI MmProbeAndLockPages(PMDLX, KPROCESSOR_MODE, LOCK_OPERATION);
+void      WINAPI MmUnmapLockedPages(void*, PMDL);
 
 static inline void *MmGetSystemAddressForMdlSafe(MDL *mdl, ULONG priority)
 {