diff --git a/api/domain_new.go b/api/domain_new.go
index 7dbba13..1248b23 100644
--- a/api/domain_new.go
+++ b/api/domain_new.go
@@ -2,6 +2,7 @@ package main
 
 import (
 	"net/http"
+	"strings"
 	"time"
 )
 
@@ -10,6 +11,10 @@ func domainNew(ownerHex string, name string, domain string) error {
 		return errorMissingField
 	}
 
+	if strings.Contains(domain, "/") {
+		return errorInvalidDomain
+	}
+
 	statement := `
 		INSERT INTO
 		domains (ownerHex, name, domain, creationDate)
diff --git a/api/errors.go b/api/errors.go
index a53695a..d044fdb 100644
--- a/api/errors.go
+++ b/api/errors.go
@@ -45,3 +45,4 @@ var errorThreadLocked = errors.New("This thread is locked. You cannot add new co
 var errorDatabaseMigration = errors.New("Encountered error applying database migration.")
 var errorNoSuchUnsubscribeSecretHex = errors.New("Invalid unsubscribe link.")
 var errorEmptyPaths = errors.New("Empty paths field.")
+var errorInvalidDomain = errors.New("Invalid domain name. Do not include the URL path after the forward slash.")