diff --git a/reactos/include/ndk/ifssupp.h b/reactos/include/ndk/ifssupp.h
index 15e58332c93..fe31f330582 100644
--- a/reactos/include/ndk/ifssupp.h
+++ b/reactos/include/ndk/ifssupp.h
@@ -27,7 +27,28 @@ typedef enum _TOKEN_TYPE
     TokenImpersonation
 } TOKEN_TYPE, *PTOKEN_TYPE;
 
-typedef PVOID PRTL_HEAP_PARAMETERS;
+typedef NTSTATUS
+(NTAPI * PRTL_HEAP_COMMIT_ROUTINE)(
+    IN PVOID Base,
+    IN OUT PVOID *CommitAddress,
+    IN OUT PSIZE_T CommitSize
+);
+
+typedef struct _RTL_HEAP_PARAMETERS
+{
+    ULONG Length;
+    SIZE_T SegmentReserve;
+    SIZE_T SegmentCommit;
+    SIZE_T DeCommitFreeBlockThreshold;
+    SIZE_T DeCommitTotalFreeThreshold;
+    SIZE_T MaximumAllocationSize;
+    SIZE_T VirtualMemoryThreshold;
+    SIZE_T InitialCommit;
+    SIZE_T InitialReserve;
+    PRTL_HEAP_COMMIT_ROUTINE CommitRoutine;
+    SIZE_T Reserved[2];
+} RTL_HEAP_PARAMETERS, *PRTL_HEAP_PARAMETERS;
+
 typedef PVOID PFS_FILTER_CALLBACKS;
 typedef USHORT SECURITY_DESCRIPTOR_CONTROL, *PSECURITY_DESCRIPTOR_CONTROL;