Index: libs/program_options/test/parsers_test.cpp
===================================================================
--- libs/program_options/test/parsers_test.cpp	(Revision 57536)
+++ libs/program_options/test/parsers_test.cpp	(Arbeitskopie)
@@ -117,6 +117,7 @@
                           "--plug3=10"};
     vector<string> cmdline3 = sv(cmdline3_,
                                  sizeof(cmdline3_)/sizeof(const char*));
+                                 
     vector<option> a3 = 
         command_line_parser(cmdline3).options(desc).run().options;
                        
@@ -202,6 +203,7 @@
     desc.add_options()
         ("gv1", new untyped_value)
         ("gv2", new untyped_value)
+        ("empty_value", new untyped_value)
         ("plug*", new untyped_value)
         ("m1.v1", new untyped_value)
         ("m1.v2", new untyped_value)
@@ -210,6 +212,7 @@
 
     const char content1[] =
     " gv1 = 0#asd\n"
+    "empty_value = \n"
     "plug3 = 7\n"
     "b = true\n"
     "[m1]\n"
@@ -220,12 +223,13 @@
 
     stringstream ss(content1);
     vector<option> a1 = parse_config_file(ss, desc).options;
-    BOOST_REQUIRE(a1.size() == 5);
+    BOOST_REQUIRE(a1.size() == 6);
     check_value(a1[0], "gv1", "0");
-    check_value(a1[1], "plug3", "7");
-    check_value(a1[2], "b", "true");
-    check_value(a1[3], "m1.v1", "1");
-    check_value(a1[4], "m1.v2", "2");
+    check_value(a1[1], "empty_value", "");
+    check_value(a1[2], "plug3", "7");
+    check_value(a1[3], "b", "true");
+    check_value(a1[4], "m1.v1", "1");
+    check_value(a1[5], "m1.v2", "2");
 
 }
 
Index: libs/program_options/src/config_file.cpp
===================================================================
--- libs/program_options/src/config_file.cpp	(Revision 57536)
+++ libs/program_options/src/config_file.cpp	(Arbeitskopie)
@@ -105,10 +105,7 @@
                     bool registered = allowed_option(name);
                     if (!registered && !m_allow_unregistered)
                         boost::throw_exception(unknown_option(name));
-                                        
-                    if (value.empty())
-                        boost::throw_exception(invalid_syntax(s, "no value given"));
-                    
+                                                   
                     found = true;
                     this->value().string_key = name;
                     this->value().value.clear();