diff --git a/dlls/ntdll/sync.c b/dlls/ntdll/sync.c
index 46cbca78679..e949df62946 100644
--- a/dlls/ntdll/sync.c
+++ b/dlls/ntdll/sync.c
@@ -510,7 +510,7 @@ NTSTATUS WINAPI NtReleaseMutant( IN HANDLE handle, OUT PLONG prev_count OPTIONAL
     {
         req->handle = wine_server_obj_handle( handle );
         status = wine_server_call( req );
-        if (prev_count) *prev_count = reply->prev_count;
+        if (prev_count) *prev_count = 1 - reply->prev_count;
     }
     SERVER_END_REQ;
     return status;
diff --git a/dlls/ntdll/tests/om.c b/dlls/ntdll/tests/om.c
index 2bc4ccdcafd..64a16abb624 100644
--- a/dlls/ntdll/tests/om.c
+++ b/dlls/ntdll/tests/om.c
@@ -1942,12 +1942,12 @@ static void test_mutant(void)
     prev = 0xdeadbeef;
     status = pNtReleaseMutant(mutant, &prev);
     ok( status == STATUS_SUCCESS, "NtQueryRelease failed %08x\n", status );
-    todo_wine ok( prev == -1, "NtQueryRelease failed, expected -1, got %d\n", prev );
+    ok( prev == -1, "NtQueryRelease failed, expected -1, got %d\n", prev );
 
     prev = 0xdeadbeef;
     status = pNtReleaseMutant(mutant, &prev);
     ok( status == STATUS_SUCCESS, "NtQueryRelease failed %08x\n", status );
-    todo_wine ok( prev == 0, "NtQueryRelease failed, expected 0, got %d\n", prev );
+    ok( prev == 0, "NtQueryRelease failed, expected 0, got %d\n", prev );
 
     memset(&info, 0xcc, sizeof(info));
     status = pNtQueryMutant(mutant, MutantBasicInformation, &info, sizeof(info), NULL);