diff --git a/include/oopless-parser.hpp b/include/oopless-parser.hpp
index c93856d..2677d60 100644
--- a/include/oopless-parser.hpp
+++ b/include/oopless-parser.hpp
@@ -25,12 +25,7 @@ void write(const std::vector<std::string> &,
            void (*f) (std::stringstream &, const std::vector<TPlanePoints> &),
            EntityConverter &);
 
-void parse_prefab(std::ifstream &, 
-                  std::ofstream &,
-                  void (*f) (std::stringstream &, const std::vector<TPlanePoints> &),
-                  std::vector<std::vector<std::string> > &);
-
-bool convertmap(const char * const, 
+bool convertmap(std::stringstream &, 
                 const char * const,
                 void (*f) (std::stringstream &, const std::vector<TPlanePoints> &),
                 std::vector<std::vector<std::string> > &);
@@ -180,4 +175,19 @@ using namespace std;
     return output;
 }
 
-#endif
\ No newline at end of file
+template <class ISTR>
+void parse_prefab(ISTR &f, 
+                  std::ofstream &out, 
+                  void (*b) (std::stringstream &, const std::vector<TPlanePoints> &),
+                  std::vector<std::vector<std::string> > &entities) {
+    using namespace std;
+    string l;
+    getline(f, l);
+    if (l.find(KEYWORD_BRUSH) != string::npos) {
+        write(parse_brush<ISTR>(f), out, b);
+    } else if (l.find(KEYWORD_ENTITY) != string::npos) {
+        entities.push_back(get_entity<ISTR>(f));
+    }
+}
+
+#endif
diff --git a/src/main.cpp b/src/main.cpp
index 2830e00..529e0b8 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -57,6 +57,22 @@ cxxopts::Options arguments(int ac, char ** av) {
     return o;
 }
 
+stringstream loadmap(const char *filename) {
+    ifstream fin;
+    fin.open(filename);
+    if (!fin.good()) {
+        cout << "error: can not open input file." << endl;
+    }
+    vector<string> v;
+    string line;
+    stringstream output;
+    while (getline(fin, line)) {
+        v.push_back(line);
+    }
+    move(v.begin(), v.end(), ostream_iterator<string>(output, "\n"));
+    return output;
+}
+
 bool convert_worldspawn(const cxxopts::Options &o, 
                         vector<vector<string> > &q) {
     bool     is_ok  = false;
@@ -64,9 +80,11 @@ bool convert_worldspawn(const cxxopts::Options &o,
     if (o.count(ARG_BRUSHFORMAT)) {
         fn = &brushdef_gtk;
     }
+    string inputfile = o[ARG_INPUT_SHORTALIAS].as<string>();
+    stringstream mapdata = loadmap(inputfile.c_str());
     try {
         is_ok = convertmap(
-                    o[ARG_INPUT_SHORTALIAS].as<string>().c_str(),  // in file
+                    mapdata,  // in file
                     o[ARG_OUTPUT_SHORTALIAS].as<string>().c_str(), // out file
                     fn,   // brush definition
                     q);   // queue of entities
diff --git a/src/oopless-parser.cpp b/src/oopless-parser.cpp
index a196697..4ce5cf8 100644
--- a/src/oopless-parser.cpp
+++ b/src/oopless-parser.cpp
@@ -101,29 +101,10 @@ void write(const vector<string> &entity,
     fo << "}" << endl;
 }
 
-void parse_prefab(ifstream &f, 
-                  ofstream &out, 
-                  void (*b) (stringstream &, const vector<TPlanePoints> &),
-                  vector<vector<string> > &entities) {
-    string l;
-    getline(f, l);
-    if (l.find(KEYWORD_BRUSH) != string::npos) {
-        write(parse_brush<ifstream>(f), out, b);
-    } else if (l.find(KEYWORD_ENTITY) != string::npos) {
-        entities.push_back(get_entity<ifstream>(f));
-    }
-}
-
-bool convertmap(const char * const infile, 
+bool convertmap(stringstream &mapdata, 
                 const char * const outfile,
                 void (*brushdef) (stringstream &, const vector<TPlanePoints> &),
                 vector<vector<string> > &entities) {
-    ifstream fin;
-    fin.open(infile);
-    if (!fin.good()){
-        cerr << "error: failed to open input file" << endl;
-        return false;
-    }
     ofstream fout;
     fout.open(outfile);
     if (!fout.good()) {
@@ -133,18 +114,17 @@ bool convertmap(const char * const infile,
     fout << "{\n"
          << "\"classname\" \"worldspawn\"" << endl;
     string line;
-    while (getline(fin, line)) {
+    while (getline(mapdata, line)) {
         if (line.find(KEYWORD_PREFAB) != string::npos ||
             line.find(KEYWORD_GLOBAL) != string::npos) {
-                parse_prefab(fin, fout, brushdef, entities);
+                parse_prefab<stringstream>(mapdata, fout, brushdef, entities);
         } else if (line.find(KEYWORD_ENTITY) != string::npos) {
-                entities.push_back(get_entity<ifstream>(fin));
+                entities.push_back(get_entity<stringstream>(mapdata));
         } else if (line.find(KEYWORD_BRUSH) != string::npos) {
-                write(parse_brush<ifstream>(fin), fout, brushdef);
+                write(parse_brush<stringstream>(mapdata), fout, brushdef);
         }
     }
     fout << "}" << endl;
-    fin.close();
     fout.close();
     return true;
 }