diff --git a/patches/llvm/21.1.1/01-Fix-WaitForSingleObject-cast-on-MinGW.patch b/patches/llvm/21.1.1/01-Fix-WaitForSingleObject-cast-on-MinGW.patch
new file mode 100644
index 0000000..8e739d8
--- /dev/null
+++ b/patches/llvm/21.1.1/01-Fix-WaitForSingleObject-cast-on-MinGW.patch
@@ -0,0 +1,13 @@
+diff --git a/lldb/source/Host/windows/MainLoopWindows.cpp b/lldb/source/Host/windows/MainLoopWindows.cpp
+index c0b10797e..e971b8cfd 100644
+--- a/lldb/source/Host/windows/MainLoopWindows.cpp
++++ b/lldb/source/Host/windows/MainLoopWindows.cpp
+@@ -58,7 +58,7 @@ public:
+       // Keep trying to cancel ReadFile() until the thread exits.
+       do {
+         CancelIoEx(m_handle, /*lpOverlapped=*/NULL);
+-      } while (WaitForSingleObject(m_monitor_thread.native_handle(), 1) ==
++      } while (WaitForSingleObject((HANDLE)m_monitor_thread.native_handle(), 1) ==
+                WAIT_TIMEOUT);
+       m_monitor_thread.join();
+     }