diff --git a/src/ast/seq_decl_plugin.cpp b/src/ast/seq_decl_plugin.cpp
index 059fe9674..90fd3fb22 100644
--- a/src/ast/seq_decl_plugin.cpp
+++ b/src/ast/seq_decl_plugin.cpp
@@ -830,6 +830,8 @@ void seq_decl_plugin::get_sort_names(svector<builtin_name> & sort_names, symbol
     init();
     sort_names.push_back(builtin_name("Seq",   SEQ_SORT));
     sort_names.push_back(builtin_name("RegEx", RE_SORT));
+    // SMT-LIB 2.5 compatibility
+    sort_names.push_back(builtin_name("String", _STRING_SORT));
     sort_names.push_back(builtin_name("StringSequence", _STRING_SORT));
 }