diff --git a/include/argparse.hpp b/include/argparse.hpp
index 3fca9fb..69cc370 100644
--- a/include/argparse.hpp
+++ b/include/argparse.hpp
@@ -462,10 +462,13 @@ class ArgumentParser {
               auto tArgument = tIterator->second;
               it = tArgument->consume(it, end, tCurrentArgument);
             }
+            else {
+              throw std::runtime_error("Unknown argument");
+            }
           }
         }
         else {
-          ++it;
+          throw std::runtime_error("Unknown argument");
         }
       }
     }
diff --git a/test/test_invalid_arguments.hpp b/test/test_invalid_arguments.hpp
index f466be8..1806816 100644
--- a/test/test_invalid_arguments.hpp
+++ b/test/test_invalid_arguments.hpp
@@ -34,5 +34,5 @@ TEST_CASE("Parse unknown optional argument", "[compound_arguments]") {
     .action([](const std::string& val) { return std::stoull(val); })
     .help("memory in MB to give the VMM when loading");
 
-  bfm.parse_args({ "./test.exe", "-om" });
+  REQUIRE_THROWS(bfm.parse_args({ "./test.exe", "-om" }));
 }