diff --git a/all_test.go b/all_test.go
index 2844d48..ae1b5c8 100644
--- a/all_test.go
+++ b/all_test.go
@@ -62,6 +62,26 @@ var uastrings = []struct {
 		ua:       "Facebot",
 		expected: "Browser:Facebot Bot:true Mobile:false",
 	},
+	{
+		title:    "NutchCVS",
+		ua:       "NutchCVS/0.8-dev (Nutch; http://lucene.apache.org/nutch/bot.html; nutch-agent@lucene.apache.org)",
+		expected: "Browser:NutchCVS Bot:true Mobile:false",
+	},
+	{
+		title:    "MJ12bot",
+		ua:       "Mozilla/5.0 (compatible; MJ12bot/v1.2.4; http://www.majestic12.co.uk/bot.php?+)",
+		expected: "Mozilla:5.0 Browser:MJ12bot-v1.2.4 Bot:true Mobile:false",
+	},
+	{
+		title:    "MJ12bot",
+		ua:       "MJ12bot/v1.0.8 (http://majestic12.co.uk/bot.php?+)",
+		expected: "Browser:MJ12bot Bot:true Mobile:false",
+	},
+	{
+		title:    "AhrefsBot",
+		ua:       "Mozilla/5.0 (compatible; AhrefsBot/4.0; +http://ahrefs.com/robot/)",
+		expected: "Mozilla:5.0 Browser:AhrefsBot-4.0 Bot:true Mobile:false",
+	},
 
 	// Internet Explorer
 	{
diff --git a/bot.go b/bot.go
index df0b6cc..8780bf4 100644
--- a/bot.go
+++ b/bot.go
@@ -75,6 +75,8 @@ func (p *UserAgent) fixOther(sections []section) {
 	}
 }
 
+var botRegex = regexp.MustCompile("(?i)(bot|crawler|sp(i|y)der|search|worm|fetch|nutch)")
+
 // Check if we're dealing with a bot or with some weird browser. If that is the
 // case, the receiver will be modified accordingly.
 func (p *UserAgent) checkBot(sections []section) {
@@ -83,9 +85,8 @@ func (p *UserAgent) checkBot(sections []section) {
 	if len(sections) == 1 && sections[0].name != "Mozilla" {
 		p.mozilla = ""
 
-		// Check whether the name has some suspicious "bot" in his name.
-		reg, _ := regexp.Compile("(?i)bot")
-		if reg.Match([]byte(sections[0].name)) {
+		// Check whether the name has some suspicious "bot" or "crawler" in his name.
+		if botRegex.Match([]byte(sections[0].name)) {
 			p.setSimple(sections[0].name, "", true)
 			return
 		}