diff --git a/libstdc++-v3/ChangeLog b/libstdc++-v3/ChangeLog
index bd0a0b3b2ab..df67836a082 100644
--- a/libstdc++-v3/ChangeLog
+++ b/libstdc++-v3/ChangeLog
@@ -1,3 +1,8 @@
+2018-05-10  Jason Merrill  <jason@redhat.com>
+
+	* include/bits/regex_compiler.h (_S_cache_size): Change from
+	function to variable.
+
 2018-05-10  Edward Smith-Rowland  <3dw4rd@verizon.net>
 
 	PR libstdc++/83140 - assoc_legendre returns negated value when m is odd
diff --git a/libstdc++-v3/include/bits/regex_compiler.h b/libstdc++-v3/include/bits/regex_compiler.h
index 7e5c2073554..6eee9cb9072 100644
--- a/libstdc++-v3/include/bits/regex_compiler.h
+++ b/libstdc++-v3/include/bits/regex_compiler.h
@@ -527,14 +527,12 @@ namespace __detail
       typedef typename std::is_same<_CharT, char>::type _UseCache;
 
       static constexpr size_t
-      _S_cache_size()
-      {
-	return 1ul << (sizeof(_CharT) * __CHAR_BIT__ * int(_UseCache::value));
-      }
+      _S_cache_size =
+	1ul << (sizeof(_CharT) * __CHAR_BIT__ * int(_UseCache::value));
 
       struct _Dummy { };
       typedef typename std::conditional<_UseCache::value,
-					std::bitset<_S_cache_size()>,
+					std::bitset<_S_cache_size>,
 					_Dummy>::type _CacheT;
       typedef typename std::make_unsigned<_CharT>::type _UnsignedCharT;