diff --git a/dlls/xaudio2_7/xapo.c b/dlls/xaudio2_7/xapo.c
index ccad417ea5c..3ccb3f190b0 100644
--- a/dlls/xaudio2_7/xapo.c
+++ b/dlls/xaudio2_7/xapo.c
@@ -175,7 +175,7 @@ static void WINAPI XAPOFX_UnlockForProcess(IXAPO *iface)
 static void WINAPI XAPOFX_Process(IXAPO *iface, UINT32 in_params_count,
         const XAPO_PROCESS_BUFFER_PARAMETERS *in_params,
         UINT32 out_params_count,
-        const XAPO_PROCESS_BUFFER_PARAMETERS *out_params, BOOL enabled)
+        XAPO_PROCESS_BUFFER_PARAMETERS *out_params, BOOL enabled)
 {
     XA2XAPOFXImpl *This = impl_from_IXAPO(iface);
     TRACE("%p, %u, %p, %u, %p, %u\n", This, in_params_count, in_params,
diff --git a/include/xapo.idl b/include/xapo.idl
index 9c3ad15134c..7b28ac9f439 100644
--- a/include/xapo.idl
+++ b/include/xapo.idl
@@ -118,7 +118,7 @@ interface IXAPO : IUnknown
     void UnlockForProcess(void);
 
     void Process(UINT32 in_params_count, const XAPO_PROCESS_BUFFER_PARAMETERS *in_params,
-        UINT32 out_params_count, const XAPO_PROCESS_BUFFER_PARAMETERS *out_params,
+        UINT32 out_params_count, XAPO_PROCESS_BUFFER_PARAMETERS *out_params,
         BOOL enabled);
 
     UINT32 CalcInputFrames(UINT32 output_frames);