diff --git a/src/coreclr/interop/comwrappers.cpp b/src/coreclr/interop/comwrappers.cpp
index 095f098e286015..58b83368f7bf4b 100644
--- a/src/coreclr/interop/comwrappers.cpp
+++ b/src/coreclr/interop/comwrappers.cpp
@@ -736,7 +736,9 @@ HRESULT ManagedObjectWrapper::QueryInterface(
                     return E_NOINTERFACE;
 
                 default:
+#if !defined(__clang__) || (__clang_major__ > 13) // Workaround bug in old clang
                     _ASSERTE(false && "Unknown result value");
+#endif
                     FALLTHROUGH;
                 case TryInvokeICustomQueryInterfaceResult::FailedToInvoke:
                     // Set the 'lacks' flag since our attempt to use ICustomQueryInterface
diff --git a/src/coreclr/pal/inc/pal.h b/src/coreclr/pal/inc/pal.h
index 9a1d25515bb32e..70b934a8ccd88e 100644
--- a/src/coreclr/pal/inc/pal.h
+++ b/src/coreclr/pal/inc/pal.h
@@ -184,14 +184,6 @@ extern bool g_arm64_atomics_present;
 #define __has_cpp_attribute(x) (0)
 #endif
 
-#ifndef FALLTHROUGH
-#if __has_cpp_attribute(fallthrough)
-#define FALLTHROUGH [[fallthrough]]
-#else // __has_cpp_attribute(fallthrough)
-#define FALLTHROUGH
-#endif // __has_cpp_attribute(fallthrough)
-#endif // FALLTHROUGH
-
 /******************* PAL-Specific Entrypoints *****************************/
 
 #define IsDebuggerPresent PAL_IsDebuggerPresent