Index: contrib/bc/include/status.h
===================================================================
--- contrib/bc/include/status.h
+++ contrib/bc/include/status.h
@@ -165,7 +165,7 @@
 #define BC_MUST_RETURN
 #endif // __STDC_VERSION__
 
-#if defined(__clang__) || defined(__GNUC__)
+#if defined(__clang__) || (defined(__GNUC__) && __GNUC__ >= 7)
 #define BC_FALLTHROUGH __attribute__((fallthrough));
 #else // defined(__clang__) || defined(__GNUC__)
 #define BC_FALLTHROUGH