diff --git a/src/c99-flex.skl b/src/c99-flex.skl
index 9efbadad..d9c1ff52 100644
--- a/src/c99-flex.skl
+++ b/src/c99-flex.skl
@@ -52,7 +52,19 @@ m4_define([[M4_HOOK_STATE_ENTRY_FORMAT]], [[	&yy_transition[$1],
 ]])
 m4_define([[M4_HOOK_NORMAL_STATE_CASE_ARM]], [[	case $1:]])
 m4_define([[M4_HOOK_EOF_STATE_CASE_ARM]], [[	case YY_STATE_EOF($1):]])
-m4_define([[M4_HOOK_EOF_STATE_CASE_FALLTHROUGH]], [[		/* FALLTHROUGH */]])
+m4_define([[M4_HOOK_EOF_STATE_CASE_FALLTHROUGH]], [[
+m4_changequote(<<, >>)
+	#if defined(__has_c_attribute)
+	#if __has_c_attribute(fallthrough)
+	[[fallthrough]];
+	#endif
+	#elif defined(__has_attribute)
+	#if __has_attribute (fallthrough)
+	__attribute__((fallthrough));
+	#endif
+	#endif
+m4_changequote([[, ]])
+]])
 m4_define([[M4_HOOK_EOF_STATE_CASE_TERMINATE]], [[		yyterminate();
 ]])
 m4_define([[M4_HOOK_TAKE_YYTEXT]], [[yy_do_before_action(yyscanner, yy_cp, yy_bp); /* set up yytext */]])
diff --git a/src/cpp-flex.skl b/src/cpp-flex.skl
index 9a84d77f..a94f07ad 100644
--- a/src/cpp-flex.skl
+++ b/src/cpp-flex.skl
@@ -42,7 +42,19 @@ m4_define([[M4_HOOK_STATE_ENTRY_FORMAT]], [[	&yy_transition[$1],
 ]])
 m4_define([[M4_HOOK_NORMAL_STATE_CASE_ARM]], [[	case $1:]])
 m4_define([[M4_HOOK_EOF_STATE_CASE_ARM]], [[	case YY_STATE_EOF($1):]])
-m4_define([[M4_HOOK_EOF_STATE_CASE_FALLTHROUGH]], [[		/* FALLTHROUGH */]])
+m4_define([[M4_HOOK_EOF_STATE_CASE_FALLTHROUGH]], [[
+m4_changequote(<<, >>)
+	#if defined(__has_cpp_attribute)
+	#if __has_cpp_attribute(fallthrough)
+	[[fallthrough]];
+	#endif
+	#elif defined(__has_attribute)
+	#if __has_attribute (fallthrough)
+	__attribute__((fallthrough));
+	#endif
+	#endif
+m4_changequote([[, ]])
+]])
 m4_define([[M4_HOOK_EOF_STATE_CASE_TERMINATE]], [[		yyterminate();
 ]])
 m4_define([[M4_HOOK_TAKE_YYTEXT]], [[YY_DO_BEFORE_ACTION; /* set up yytext */]])
diff --git a/src/main.c b/src/main.c
index 56ca8ae3..9d1bcabf 100644
--- a/src/main.c
+++ b/src/main.c
@@ -239,10 +239,12 @@ int flex_main (int argc, char *argv[])
 	/* generate cases for any missing EOF rules */
 	for (i = 1; i <= lastsc; ++i)
 		if (!sceof[i]) {
+			if (did_eof_rule) {
+				out ("M4_HOOK_EOF_STATE_CASE_FALLTHROUGH");
+				outc('\n');
+			}
 			out_str ("M4_HOOK_EOF_STATE_CASE_ARM(%s)", scname[i]);
 			outc('\n');
-			out ("M4_HOOK_EOF_STATE_CASE_FALLTHROUGH");
-			outc('\n');
 			did_eof_rule = true;
 		}