diff --git a/spec/line_editor/readline_spec.rb b/spec/line_editor/readline_spec.rb
index 86cf7466e..7ab67aaa9 100644
--- a/spec/line_editor/readline_spec.rb
+++ b/spec/line_editor/readline_spec.rb
@@ -2,6 +2,8 @@
 
 describe Thor::LineEditor::Readline do
   before do
+    # Eagerly check Readline availability before mocking
+    Thor::LineEditor::Readline.available?
     unless defined? ::Readline
       ::Readline = double("Readline")
       allow(::Readline).to receive(:completion_append_character=).with(nil)