diff --git a/reactos/base/services/umpnpmgr/umpnpmgr.c b/reactos/base/services/umpnpmgr/umpnpmgr.c
index dc4463c1949..64d8b45cd2f 100644
--- a/reactos/base/services/umpnpmgr/umpnpmgr.c
+++ b/reactos/base/services/umpnpmgr/umpnpmgr.c
@@ -1855,7 +1855,12 @@ DWORD PNP_SetHwProf(
 
 /* Function 56 */
 DWORD PNP_QueryArbitratorFreeData(
-    handle_t hBinding)
+    handle_t hBinding,
+    BYTE *pData,
+    DWORD DataLen,
+    LPWSTR pDeviceID,
+    RESOURCEID ResourceID,
+    DWORD ulFlags)
 {
     UNIMPLEMENTED;
     return CR_CALL_NOT_IMPLEMENTED;
@@ -1864,7 +1869,11 @@ DWORD PNP_QueryArbitratorFreeData(
 
 /* Function 57 */
 DWORD PNP_QueryArbitratorFreeSize(
-    handle_t hBinding)
+    handle_t hBinding,
+    DWORD *pulSize,
+    LPWSTR pDeviceID,
+    RESOURCEID ResourceID,
+    DWORD ulFlags)
 {
     UNIMPLEMENTED;
     return CR_CALL_NOT_IMPLEMENTED;
diff --git a/reactos/include/reactos/idl/pnp.idl b/reactos/include/reactos/idl/pnp.idl
index daef2a2b235..b776e6d4a78 100644
--- a/reactos/include/reactos/idl/pnp.idl
+++ b/reactos/include/reactos/idl/pnp.idl
@@ -731,11 +731,20 @@ interface pnp
 
     /* Function 56 */
     DWORD PNP_QueryArbitratorFreeData(
-        [in] handle_t hBinding);
+        [in] handle_t hBinding,
+        [out,size_is(DataLen)] BYTE *pData,
+        [in] DWORD DataLen,
+        [in, string, ref] LPWSTR pDeviceID,
+        [in] RESOURCEID ResourceID,
+        [in] DWORD ulFlags);
 
     /* Function 57 */
     DWORD PNP_QueryArbitratorFreeSize(
-        [in] handle_t hBinding);
+        [in] handle_t hBinding,
+        [out] DWORD *pulSize,
+        [in, string, ref] LPWSTR pDeviceID,
+        [in] RESOURCEID ResourceID,
+        [in] DWORD ulFlags);
 
     /* Function 58 */
     DWORD PNP_RunDetection(