diff --git a/cc/config/clang.go b/cc/config/clang.go
index 5e22d6a..5cf2421 100644
--- a/cc/config/clang.go
+++ b/cc/config/clang.go
@@ -103,6 +103,10 @@
 	pctx.StaticVariable("ClangExtraCflags", strings.Join([]string{
 		"-D__compiler_offsetof=__builtin_offsetof",
 
+		// Make implicit fallthrough an error in the future.
+		"-Wimplicit-fallthrough",
+		"-Wno-error=implicit-fallthrough",
+
 		// Help catch common 32/64-bit errors.
 		"-Werror=int-conversion",