diff --git a/dlls/ntoskrnl.exe/ntoskrnl.exe.spec b/dlls/ntoskrnl.exe/ntoskrnl.exe.spec
index d3e60701492..ab952e528b6 100644
--- a/dlls/ntoskrnl.exe/ntoskrnl.exe.spec
+++ b/dlls/ntoskrnl.exe/ntoskrnl.exe.spec
@@ -166,7 +166,7 @@
 @ stdcall ExInterlockedRemoveHeadList(ptr ptr)
 @ stub ExIsProcessorFeaturePresent
 @ stdcall ExIsResourceAcquiredExclusiveLite(ptr)
-@ stub ExIsResourceAcquiredSharedLite
+@ stdcall ExIsResourceAcquiredSharedLite(ptr)
 @ stdcall ExLocalTimeToSystemTime(ptr ptr) RtlLocalTimeToSystemTime
 @ stub ExNotifyCallback
 @ stub ExQueryPoolBlockSize
diff --git a/dlls/ntoskrnl.exe/sync.c b/dlls/ntoskrnl.exe/sync.c
index 94b97786022..fbe9dbe9da9 100644
--- a/dlls/ntoskrnl.exe/sync.c
+++ b/dlls/ntoskrnl.exe/sync.c
@@ -1144,3 +1144,28 @@ BOOLEAN WINAPI ExIsResourceAcquiredExclusiveLite( ERESOURCE *resource )
 
     return ret;
 }
+
+/***********************************************************************
+ *           ExIsResourceAcquiredSharedLite   (NTOSKRNL.EXE.@)
+ */
+ULONG WINAPI ExIsResourceAcquiredSharedLite( ERESOURCE *resource )
+{
+    ULONG ret;
+    KIRQL irql;
+
+    TRACE("resource %p.\n", resource);
+
+    KeAcquireSpinLock( &resource->SpinLock, &irql );
+
+    if (resource->OwnerEntry.OwnerThread == (ERESOURCE_THREAD)KeGetCurrentThread())
+        ret = resource->ActiveEntries;
+    else
+    {
+        OWNER_ENTRY *entry = resource_get_shared_entry( resource, (ERESOURCE_THREAD)KeGetCurrentThread() );
+        ret = entry->OwnerCount;
+    }
+
+    KeReleaseSpinLock( &resource->SpinLock, irql );
+
+    return ret;
+}
diff --git a/include/ddk/wdm.h b/include/ddk/wdm.h
index 5a84602d43e..dae83afb2ee 100644
--- a/include/ddk/wdm.h
+++ b/include/ddk/wdm.h
@@ -1532,6 +1532,7 @@ PSLIST_ENTRY WINAPI ExInterlockedPopEntrySList(PSLIST_HEADER,PKSPIN_LOCK);
 PSLIST_ENTRY WINAPI ExInterlockedPushEntrySList(PSLIST_HEADER,PSLIST_ENTRY,PKSPIN_LOCK);
 LIST_ENTRY * WINAPI ExInterlockedRemoveHeadList(LIST_ENTRY*,KSPIN_LOCK*);
 BOOLEAN   WINAPI ExIsResourceAcquiredExclusiveLite(ERESOURCE*);
+ULONG     WINAPI ExIsResourceAcquiredSharedLite(ERESOURCE*);
 void      WINAPI ExReleaseFastMutexUnsafe(PFAST_MUTEX);
 void      WINAPI ExReleaseResourceForThreadLite(ERESOURCE*,ERESOURCE_THREAD);
 ULONG     WINAPI ExSetTimerResolution(ULONG,BOOLEAN);