diff --git a/include/argparse.hpp b/include/argparse.hpp
index b551865..771a54c 100644
--- a/include/argparse.hpp
+++ b/include/argparse.hpp
@@ -321,7 +321,7 @@ private:
 
   // If an argument starts with "-" or "--", then it's optional
   static bool is_optional(const std::string &aName) {
-    return (!aName.empty() && aName[0] == '-' && !is_integer(aName) &&
+    return (aName.size() > 1 && aName[0] == '-' && !is_integer(aName) &&
             !is_float(aName));
   }
 
diff --git a/test/test_optional_arguments.cpp b/test/test_optional_arguments.cpp
index 2cb7395..8daf58a 100644
--- a/test/test_optional_arguments.cpp
+++ b/test/test_optional_arguments.cpp
@@ -12,6 +12,13 @@ DOCTEST_TEST_CASE("Parse toggle arguments with default value [optional_arguments
   REQUIRE(program["--verbose"] == false);
 }
 
+DOCTEST_TEST_CASE("Argument '-' is not an optional argument [optional_arguments]") {
+  argparse::ArgumentParser program("test");
+  program.add_argument("input");
+  program.parse_args({ "./test.exe", "-"});
+  REQUIRE(program.get<std::string>("input") == "-");
+}
+
 DOCTEST_TEST_CASE("Parse toggle arguments with implicit value [optional_arguments]") {
   argparse::ArgumentParser program("test");
   program.add_argument("--verbose")