diff --git a/src/msw/dirdlg.cpp b/src/msw/dirdlg.cpp
index 84557d7c95..b0b9ed84d9 100644
--- a/src/msw/dirdlg.cpp
+++ b/src/msw/dirdlg.cpp
@@ -73,12 +73,15 @@ struct IShellItem : public IUnknown
 
 #endif // #ifndef __IShellItem_INTERFACE_DEFINED__
 
+#if defined(__VISUALC__) || !defined(__IShellItem_INTERFACE_DEFINED__)
 // Define this GUID in any case, even when __IShellItem_INTERFACE_DEFINED__ is
 // defined in the headers we might still not have it in the actual uuid.lib,
-// this happens with at least VC7 used with its original (i.e. not updated) SDK
-// and there is no harm in defining the GUID unconditionally.
+// this happens with at least VC7 used with its original (i.e. not updated) SDK.
+// clang complains about multiple definitions, so only define it unconditionally
+// when using a Visual C compiler.
 DEFINE_GUID(IID_IShellItem,
     0x43826D1E, 0xE718, 0x42EE, 0xBC, 0x55, 0xA1, 0xE2, 0x61, 0xC3, 0x7B, 0xFE);
+#endif
 
 struct IShellItemFilter;
 struct IFileDialogEvents;