diff --git a/History.md b/History.md
index 7d94db602..9414dd7af 100644
--- a/History.md
+++ b/History.md
@@ -1,5 +1,12 @@
 # Liquid Change Log
 
+## 5.6.0 (unreleased)
+
+### Fixes
+
+* Fix Tokenizer to handle null source value (#1873) [Bahar Pourazar]
+
+
 ## 5.5.0 2024-03-21
 
 Please reference the GitHub release for more information.
diff --git a/lib/liquid/tokenizer.rb b/lib/liquid/tokenizer.rb
index cccdbf215..740f85999 100644
--- a/lib/liquid/tokenizer.rb
+++ b/lib/liquid/tokenizer.rb
@@ -5,7 +5,7 @@ class Tokenizer
     attr_reader :line_number, :for_liquid_tag
 
     def initialize(source, line_numbers = false, line_number: nil, for_liquid_tag: false)
-      @source         = source.to_s
+      @source         = source.to_s.to_str
       @line_number    = line_number || (line_numbers ? 1 : nil)
       @for_liquid_tag = for_liquid_tag
       @offset         = 0
diff --git a/lib/liquid/version.rb b/lib/liquid/version.rb
index 4be6b9775..bc8ab3e56 100644
--- a/lib/liquid/version.rb
+++ b/lib/liquid/version.rb
@@ -2,5 +2,5 @@
 # frozen_string_literal: true
 
 module Liquid
-  VERSION = "5.6.0.rc2"
+  VERSION = "5.6.0.rc3"
 end