diff --git a/ext/iconv/iconv.c b/ext/iconv/iconv.c
index 5c77299dfa6..6eb74e86532 100644
--- a/ext/iconv/iconv.c
+++ b/ext/iconv/iconv.c
@@ -146,6 +146,8 @@ PHP_MINIT_FUNCTION(miconv)
 
 #ifdef PHP_ICONV_IMPL
 	REGISTER_STRING_CONSTANT("ICONV_IMPL", PHP_ICONV_IMPL, CONST_CS | CONST_PERSISTENT);
+#elif HAVE_LIBICONV
+	REGISTER_STRING_CONSTANT("ICONV_IMPL", "libiconv", CONST_CS | CONST_PERSISTENT);
 #else
 	REGISTER_STRING_CONSTANT("ICONV_IMPL", "unknown", CONST_CS | CONST_PERSISTENT);
 #endif