diff --git a/src/mobility/helper/ns2-mobility-helper.cc b/src/mobility/helper/ns2-mobility-helper.cc
index dd815c3ec..4caa81344 100644
--- a/src/mobility/helper/ns2-mobility-helper.cc
+++ b/src/mobility/helper/ns2-mobility-helper.cc
@@ -399,7 +399,9 @@ bool
 IsNumber (const string& s)
 {
   char *endp;
-  (void) strtod (s.c_str (), &endp); // declared with warn_unused_result
+  double v = strtod (s.c_str (), &endp); // declared with warn_unused_result
+  //cast v to void, to suppress v set but not used compiler warning
+  (void) v;
   return endp == s.c_str () + s.size ();
 }
 
diff --git a/src/topology-read/model/rocketfuel-topology-reader.cc b/src/topology-read/model/rocketfuel-topology-reader.cc
index d28908eb7..ec7eada25 100644
--- a/src/topology-read/model/rocketfuel-topology-reader.cc
+++ b/src/topology-read/model/rocketfuel-topology-reader.cc
@@ -208,7 +208,9 @@ RocketfuelTopologyReader::GenerateFromWeightsFile (int argc, char *argv[])
 
   sname = argv[0];
   tname = argv[1];
-  (void) strtod (argv[2], &endptr); // weight
+  double v = strtod (argv[2], &endptr); // weight
+  // cast v to void , to suppress 'v' set but not used compiler warning
+  (void) v;
   if (*endptr != '\0')
     {
       NS_LOG_WARN ("invalid weight: " << argv[2]);