diff --git a/src/bindings/matlab/StructureFields.cpp b/src/bindings/matlab/StructureFields.cpp
index 0720699f68..2c324a8412 100644
--- a/src/bindings/matlab/StructureFields.cpp
+++ b/src/bindings/matlab/StructureFields.cpp
@@ -240,18 +240,18 @@ StructureFields::populateFields()
 
   // get structure returns fieldnames, default values and value types
   // fieldnames are an array of arrays giving values for several aspects of the structure 
-  // 		SBMLfieldnames = { {'typecode','','',0,0}, ...
-  //{'metaid', 'metaid', '', 1, 20}, ...
-  //{'notes', 'notes', '', 1, 1}, ...
-  //{'annotation', 'annotation', '', 1, 2}, ...
-  //{'formula', 'formula', '', 1, 5}, ...
-  //{'variable', 'variable', '', 1, 20}, ...
-  //{'species', 'species', '', 1, 20}, ...
-  //{'compartment', 'compartment', '', 1, 20}, ...
-  //{'name', 'name', '', 1, 20}, ...
-  //{'units', 'units', '', 1, 20}, ...
-  //
-  //{name of the field, sbml name, prefix, is sbml attribute, type enum}
+  // 		SBMLfieldnames = { {'typecode','','',0,0}, ...
+  //{'metaid', 'metaid', '', 1, 20}, ...
+  //{'notes', 'notes', '', 1, 1}, ...
+  //{'annotation', 'annotation', '', 1, 2}, ...
+  //{'formula', 'formula', '', 1, 5}, ...
+  //{'variable', 'variable', '', 1, 20}, ...
+  //{'species', 'species', '', 1, 20}, ...
+  //{'compartment', 'compartment', '', 1, 20}, ...
+  //{'name', 'name', '', 1, 20}, ...
+  //{'units', 'units', '', 1, 20}, ...
+  //
+  //{name of the field, sbml name, prefix, is sbml attribute, type enum}
 
   for (unsigned int i = 0; i < nNumberFields; ++i)
   {
@@ -539,10 +539,10 @@ StructureFields::getNamespacesStructure()
     * a string that is NULL
     */
     if (pacPrefix == NULL) {
-      pacPrefix = "";
+      pacPrefix = safe_strdup("");
     }
     if (pacURI == NULL) {
-      pacURI = "";
+      pacURI = safe_strdup("");
     }
 
     mxSetField(mxNSReturn, i, "prefix", mxCreateString(pacPrefix));