diff --git a/mozglue/build/WindowsDllBlocklist.cpp b/mozglue/build/WindowsDllBlocklist.cpp
index eab7531560b0..e003bc0fa423 100644
--- a/mozglue/build/WindowsDllBlocklist.cpp
+++ b/mozglue/build/WindowsDllBlocklist.cpp
@@ -303,8 +303,10 @@ printf_stderr(const char *fmt, ...)
 }
 
 
+#ifdef _M_IX86
 typedef MOZ_NORETURN_PTR void (__fastcall* BaseThreadInitThunk_func)(BOOL aIsInitialThread, void* aStartAddress, void* aThreadParam);
 static BaseThreadInitThunk_func stub_BaseThreadInitThunk = nullptr;
+#endif
 
 typedef NTSTATUS (NTAPI *LdrLoadDll_func) (PWCHAR filePath, PULONG flags, PUNICODE_STRING moduleFileName, PHANDLE handle);
 static LdrLoadDll_func stub_LdrLoadDll;
@@ -786,6 +788,7 @@ continue_loading:
   return stub_LdrLoadDll(filePath, flags, moduleFileName, handle);
 }
 
+#ifdef _M_IX86
 static bool
 ShouldBlockThread(void* aStartAddress)
 {
@@ -821,6 +824,8 @@ patched_BaseThreadInitThunk(BOOL aIsInitialThread, void* aStartAddress,
   stub_BaseThreadInitThunk(aIsInitialThread, aStartAddress, aThreadParam);
 }
 
+#endif // _M_IX86
+
 
 static WindowsDllInterceptor NtDllIntercept;
 static WindowsDllInterceptor Kernel32Intercept;
@@ -870,6 +875,8 @@ DllBlocklist_Initialize(uint32_t aInitFlags)
   }
 #endif
 
+#ifdef _M_IX86 // Minimize impact. Crashes in BaseThreadInitThunk are more frequent on x86
+
   // Bug 1361410: WRusr.dll will overwrite our hook and cause a crash.
   // Workaround: If we detect WRusr.dll, don't hook.
   if (!GetModuleHandleW(L"WRusr.dll")) {
@@ -881,6 +888,7 @@ DllBlocklist_Initialize(uint32_t aInitFlags)
 #endif
     }
   }
+#endif // _M_IX86
 }
 
 MFBT_API void
diff --git a/toolkit/xre/test/win/TestDllInterceptor.cpp b/toolkit/xre/test/win/TestDllInterceptor.cpp
index 514404ac1dc6..2c1afa9ef773 100644
--- a/toolkit/xre/test/win/TestDllInterceptor.cpp
+++ b/toolkit/xre/test/win/TestDllInterceptor.cpp
@@ -548,7 +548,9 @@ int main()
       TestHook(TestSetCursorPos, "user32.dll", "SetCursorPos") &&
       TestHook(TestTlsAlloc, "kernel32.dll", "TlsAlloc") &&
       TestHook(TestTlsFree, "kernel32.dll", "TlsFree") &&
+#ifdef _M_IX86
       TestDetour("kernel32.dll", "BaseThreadInitThunk") &&
+#endif
       TestDetour("ntdll.dll", "LdrLoadDll")) {
     printf("TEST-PASS | WindowsDllInterceptor | all checks passed\n");
     return 0;