diff --git a/src/robots.cpp b/src/robots.cpp
index c764c35..6382e8d 100644
--- a/src/robots.cpp
+++ b/src/robots.cpp
@@ -65,6 +65,9 @@ namespace Rep
         {
             if (key.compare("user-agent") == 0)
             {
+                // Store the user agent string as lowercased
+                std::transform(value.begin(), value.end(), value.begin(), ::tolower);
+
                 if (last_agent)
                 {
                     group.push_back(value);
diff --git a/test/test-robots.cpp b/test/test-robots.cpp
index bedea8e..4593845 100644
--- a/test/test-robots.cpp
+++ b/test/test-robots.cpp
@@ -122,7 +122,7 @@ TEST(RobotsTest, ExposesSitemaps)
 TEST(RobotsTest, CaseInsensitivity)
 {
     std::string content =
-        "User-agent: agent\n"
+        "User-agent: Agent\n"
         "Disallow: /path\n";
     Rep::Robots robot(content);
     EXPECT_FALSE(robot.allowed("/path", "agent"));