1 files changed, 17 insertions, 6 deletions
diff --git a/lib/rexml/namespace.rb b/lib/rexml/namespace.rb
index 4a7174eaeb..924edf9506 100644
--- a/lib/rexml/namespace.rb
+++ b/lib/rexml/namespace.rb
@@ -1,4 +1,5 @@
 # frozen_string_literal: false
+
 require_relative 'xmltokens'
 
 module REXML
@@ -14,14 +15,24 @@ module REXML
     # Sets the name and the expanded name
     def name=( name )
       @expanded_name = name
-      name =~ NAMESPLIT
-      if $1
-        @prefix = $1
+      case name
+      when NAMESPLIT
+        if $1
+          @prefix = $1
+        else
+          @prefix = ""
+          @namespace = ""
+        end
+        @name = $2
+      when ""
+        @prefix = nil
+        @namespace = nil
+        @name = nil
       else
-        @prefix = ""
-        @namespace = ""
+        message = "name must be \#{PREFIX}:\#{LOCAL_NAME} or \#{LOCAL_NAME}: "
+        message += "<#{name.inspect}>"
+        raise ArgumentError, message
       end
-      @name = $2
     end
 
     # Compares names optionally WITH namespaces