diff --git a/src/plugin/Manager.cc b/src/plugin/Manager.cc
index ab0b85676b..b891a0faab 100644
--- a/src/plugin/Manager.cc
+++ b/src/plugin/Manager.cc
@@ -79,18 +79,19 @@ void Manager::SearchDynamicPlugins(const std::string& dir)
 		std::string name;
 		std::getline(in, name);
 		strstrip(name);
+		string lower_name = strtolower(name);
 
 		if ( name.empty() )
 			reporter->FatalError("empty plugin magic file %s", magic.c_str());
 
-		if ( dynamic_plugins.find(name) != dynamic_plugins.end() )
+		if ( dynamic_plugins.find(lower_name) != dynamic_plugins.end() )
 			{
 			DBG_LOG(DBG_PLUGINS, "Found already known plugin %s in %s, ignoring", name.c_str(), dir.c_str());
 			return;
 			}
 
 		// Record it, so that we can later activate it.
-		dynamic_plugins.insert(std::make_pair(name, dir));
+		dynamic_plugins.insert(std::make_pair(lower_name, dir));
 
 		DBG_LOG(DBG_PLUGINS, "Found plugin %s in %s", name.c_str(), dir.c_str());
 		return;
@@ -135,7 +136,7 @@ void Manager::SearchDynamicPlugins(const std::string& dir)
 
 bool Manager::ActivateDynamicPluginInternal(const std::string& name, bool ok_if_not_found)
 	{
-	dynamic_plugin_map::iterator m = dynamic_plugins.find(name);
+	dynamic_plugin_map::iterator m = dynamic_plugins.find(strtolower(name));
 
 	if ( m == dynamic_plugins.end() )
 		{
@@ -230,7 +231,7 @@ bool Manager::ActivateDynamicPluginInternal(const std::string& name, bool ok_if_
 
 			// Make sure the name the plugin reports is consistent with
 			// what we expect from its magic file.
-			if ( string(current_plugin->Name()) != name )
+			if ( strtolower(current_plugin->Name()) != strtolower(name) )
 				reporter->FatalError("inconsistent plugin name: %s vs %s",
 						     current_plugin->Name().c_str(), name.c_str());
 
@@ -297,7 +298,7 @@ void Manager::UpdateInputFiles()
 
 static bool plugin_cmp(const Plugin* a, const Plugin* b)
 	{
-	return a->Name() < b->Name();
+	return strtolower(a->Name()) < strtolower(b->Name());
 	}
 
 void Manager::RegisterPlugin(Plugin *plugin)
@@ -318,10 +319,11 @@ void Manager::RegisterBifFile(const char* plugin, bif_init_func c)
 	{
 	bif_init_func_map* bifs = BifFilesInternal();
 
-	bif_init_func_map::iterator i = bifs->find(plugin);
+	std::string lower_plugin = strtolower(plugin);
+	bif_init_func_map::iterator i = bifs->find(lower_plugin);
 
 	if ( i == bifs->end() )
-		i = bifs->insert(std::make_pair(std::string(plugin), new bif_init_func_list())).first;
+		i = bifs->insert(std::make_pair(lower_plugin, new bif_init_func_list())).first;
 
 	i->second->push_back(c);
 	}
@@ -348,7 +350,7 @@ void Manager::InitBifs()
 	for ( plugin_list::iterator i = Manager::ActivePluginsInternal()->begin();
           i != Manager::ActivePluginsInternal()->end(); i++ )
 		{
-		bif_init_func_map::const_iterator b = bifs->find((*i)->Name());
+		bif_init_func_map::const_iterator b = bifs->find(strtolower((*i)->Name()));
 
 		if ( b != bifs->end() )
 			{
@@ -397,7 +399,7 @@ Manager::inactive_plugin_list Manager::InactivePlugins() const
 
 		for ( plugin_list::const_iterator j = all->begin(); j != all->end(); j++ )
 			{
-			if ( (*i).first == (*j)->Name() )
+			if ( (*i).first == strtolower((*j)->Name()) )
 				{
 				found = true;
 				break;
@@ -434,7 +436,7 @@ Manager::bif_init_func_map* Manager::BifFilesInternal()
 static bool hook_cmp(std::pair<int, Plugin*> a, std::pair<int, Plugin*> b)
 	{
 	if ( a.first == b.first )
-		return a.second->Name() < a.second->Name();
+		return strtolower(a.second->Name()) < strtolower(a.second->Name());
 
 	// Reverse sort.
 	return a.first > b.first;
diff --git a/src/util.cc b/src/util.cc
index 60a92af45f..ac2a942ed3 100644
--- a/src/util.cc
+++ b/src/util.cc
@@ -541,6 +541,13 @@ bool is_printable(const char* s, int len)
 	return true;
 	}
 
+std::string strtolower(const std::string& s)
+	{
+	std::string t = s;
+	std::transform(t.begin(), t.end(), t.begin(), ::tolower);
+	return t;
+	}
+
 const char* fmt_bytes(const char* data, int len)
 	{
 	static char buf[1024];
diff --git a/src/util.h b/src/util.h
index 50c33d5608..f65e0fb7d0 100644
--- a/src/util.h
+++ b/src/util.h
@@ -159,6 +159,9 @@ int strstr_n(const int big_len, const unsigned char* big,
 extern int fputs(int len, const char* s, FILE* fp);
 extern bool is_printable(const char* s, int len);
 
+// Return a lower-cased version of the string.
+extern std::string strtolower(const std::string& s);
+
 extern const char* fmt_bytes(const char* data, int len);
 
 // Note: returns a pointer into a shared buffer.