diff --git a/src/ast/ast_smt2_pp.cpp b/src/ast/ast_smt2_pp.cpp
index 5c3eb93c2..a38f7cd1a 100644
--- a/src/ast/ast_smt2_pp.cpp
+++ b/src/ast/ast_smt2_pp.cpp
@@ -43,6 +43,9 @@ format * smt2_pp_environment::pp_fdecl_name(symbol const & s, unsigned & len) co
         len = static_cast<unsigned>(str.length());
         return mk_string(m, str.c_str());
     }
+    else if (!s.bare_str()) {
+        return mk_string(m, "null");
+    }
     else {
         len = static_cast<unsigned>(strlen(s.bare_str()));
         return mk_string(m, s.bare_str());