1 files changed, 11 insertions, 0 deletions
diff --git a/src/libexpr/symbol-table.hh b/src/libexpr/symbol-table.hh
index 424c2353899e..976117a20a46 100644
--- a/src/libexpr/symbol-table.hh
+++ b/src/libexpr/symbol-table.hh
@@ -1,8 +1,13 @@
 #ifndef __SYMBOL_TABLE_H
 #define __SYMBOL_TABLE_H
 
+#include "config.h"
+
 #include <map>
+
+#if HAVE_TR1_UNORDERED_SET
 #include <tr1/unordered_set>
+#endif
 
 #include "types.hh"
 
@@ -23,6 +28,8 @@ private:
     friend class SymbolTable;
 
 public:
+    Symbol() : s(0) { };
+    
     bool operator == (const Symbol & s2) const
     {
         return s == s2.s;
@@ -60,7 +67,11 @@ inline std::ostream & operator << (std::ostream & str, const Symbol & sym)
 class SymbolTable
 {
 private:
+#if HAVE_TR1_UNORDERED_SET 
     typedef std::tr1::unordered_set<string> Symbols;
+#else
+    typedef std::set<string> Symbols;
+#endif
     Symbols symbols;
 
 public: