--- a/dom/media/fake-cdm/cdm-test-output-protection.h
+++ b/dom/media/fake-cdm/cdm-test-output-protection.h
@@ -37,17 +37,17 @@ static BOOL CALLBACK EnumDisplayMonitors
 
   ULONG numVideoOutputs = 0;
   IOPMVideoOutput** opmVideoOutputArray = nullptr;
   HRESULT hr = sOPMGetVideoOutputsFromHMONITORProc(hMonitor,
                                                    OPM_VOS_OPM_SEMANTICS,
                                                    &numVideoOutputs,
                                                    &opmVideoOutputArray);
   if (S_OK != hr) {
-    if (0x8007001f != hr && 0x80070032 != hr && 0xc02625e5 != hr) {
+    if ((HRESULT)0x8007001f != hr && (HRESULT)0x80070032 != hr && (HRESULT)0xc02625e5 != hr) {
       char msg[100];
       sprintf(msg, "FAIL OPMGetVideoOutputsFromHMONITOR call failed: HRESULT=0x%08x", hr);
       failureMsgs->push_back(msg);
     }
     return true;
   }
 
   DISPLAY_DEVICEA dd;