diff --git a/Misc/NEWS.d/next/Library/2026-05-25-07-22-05.gh-issue-150372.9hLqhe.rst b/Misc/NEWS.d/next/Library/2026-05-25-07-22-05.gh-issue-150372.9hLqhe.rst
new file mode 100644
index 000000000000000..9364570a954814f
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2026-05-25-07-22-05.gh-issue-150372.9hLqhe.rst
@@ -0,0 +1,3 @@
+Fix missing null check on the result of :func:`!strdup` in
+:mod:`readline` module initialization, preventing a potential null pointer
+dereference on memory allocation failure.
diff --git a/Modules/readline.c b/Modules/readline.c
index 488332f548e5fe3..419d3a36a1b161b 100644
--- a/Modules/readline.c
+++ b/Modules/readline.c
@@ -1404,6 +1404,11 @@ setup_readline(readlinestate *mod_state)
     completer_word_break_characters =
         strdup(" \t\n`~!@#$%^&*()-=+[{]}\\|;:'\",<>/?");
         /* All nonalphanums except '.' */
+
+    if (!completer_word_break_characters) {
+        RESTORE_LOCALE(saved_locale)
+        return -1;
+    }
 #ifdef WITH_EDITLINE
     // libedit uses rl_basic_word_break_characters instead of
     // rl_completer_word_break_characters as complete delimiter