Index: src/lib/symbol-table-ops.cc
--- src/lib/symbol-table-ops.cc.orig	2017-03-13 20:54:43.000000000 +0100
+++ src/lib/symbol-table-ops.cc	2017-03-14 08:18:37.871243000 +0100
@@ -6,6 +6,14 @@
 
 #include <string>
 
+#include <sstream>
+
+template <typename T> std::string my_to_string(const T& n) {
+    std::ostringstream stm;
+    stm << n;
+    return stm.str();
+}
+
 namespace fst {
 
 SymbolTable *MergeSymbolTable(const SymbolTable &left, const SymbolTable &right,
@@ -111,7 +119,7 @@
                          int64 nlabels, SymbolTable *syms) {
   for (int64 i = 0; i < nlabels; ++i) {
     auto index = i + start_label;
-    if (index != syms->AddSymbol(prefix + std::to_string(i), index)) {
+    if (index != syms->AddSymbol(prefix + my_to_string(i), index)) {
       FSTERROR() << "AddAuxiliarySymbols: Symbol table clash";
       return false;
     }
