diff --git a/src/ArgParser.cc b/src/ArgParser.cc
index 316c9c2..858b579 100644
--- a/src/ArgParser.cc
+++ b/src/ArgParser.cc
@@ -76,9 +76,9 @@ void ArgParser::parse(int argc, char ** argv) const
     longopts.push_back({0,0,0,0});
 
     {
+        opterr = 1;
         int r;
         int idx;
-        opterr = 0;
         while(true)
         {
             r = getopt_long(argc, argv, &optstring.front(), &longopts.front(), &idx); 
@@ -87,9 +87,7 @@ void ArgParser::parse(int argc, char ** argv) const
             assert(r != ':');
             if(r == '?')
             {
-                ostringstream sout;
-                assert(optopt < 256);
-                throw string() + ((opt_map.find(optopt) == opt_map.end()) ? "Unknown option: -" : "Missing argument for option -") + (char)optopt;
+                throw "";
             }    
 
             auto iter = opt_map.find(r);
diff --git a/src/pdf2htmlEX.cc b/src/pdf2htmlEX.cc
index f76b009..228ecb4 100644
--- a/src/pdf2htmlEX.cc
+++ b/src/pdf2htmlEX.cc
@@ -89,10 +89,24 @@ void parse_options (int argc, char **argv)
     {
         argparser.parse(argc, argv);
     }
+    catch(const char * s)
+    {
+        // if s == "", getopt_long would have printed the error message
+        if(s && s[0])
+        {
+            cerr << "Error when parsing the arguments:" << endl;
+            cerr << s << endl;
+        }
+        exit(EXIT_FAILURE);
+    }
     catch(const std::string & s)
     {
-        cerr << "Error when parsing the arguments:" << endl;
-        cerr << s << endl;
+        // if s == "", getopt_long would have printed the error message
+        if(s != "")
+        {
+            cerr << "Error when parsing the arguments:" << endl;
+            cerr << s << endl;
+        }
         exit(EXIT_FAILURE);
     }
 }
@@ -181,6 +195,10 @@ int main(int argc, char **argv)
 
         finished = true;
     }
+    catch (const char * s)
+    {
+        cerr << "Error: " << s << endl;
+    }
     catch (const string & s)
     {
         cerr << "Error: " << s << endl;