diff --git a/Misc/NEWS.d/next/Core_and_Builtins/2026-07-26-12-00-02.gh-issue-151673.g7h8i9.rst b/Misc/NEWS.d/next/Core_and_Builtins/2026-07-26-12-00-02.gh-issue-151673.g7h8i9.rst
new file mode 100644
index 00000000000000..1126f04790647d
--- /dev/null
+++ b/Misc/NEWS.d/next/Core_and_Builtins/2026-07-26-12-00-02.gh-issue-151673.g7h8i9.rst
@@ -0,0 +1 @@
+Fix a crash in the warnings module when allocating a synthetic filename fails under memory pressure.
diff --git a/Python/_warnings.c b/Python/_warnings.c
index 4f6de50efa14a8..af546acd2db3a5 100644
--- a/Python/_warnings.c
+++ b/Python/_warnings.c
@@ -1035,6 +1035,9 @@ setup_context(Py_ssize_t stack_level,
         globals = interp->sysdict;
         *filename = PyUnicode_FromString("<sys>");
         *lineno = 0;
+        if (*filename == NULL) {
+            return 0;  /* nothing else allocated yet on this path */
+        }
     }
     else {
         globals = f->f_frame->f_globals;