diff --git a/Misc/NEWS.d/next/Core_and_Builtins/2026-10-19-19-33-35.gh-issue-159739.09590b.rst b/Misc/NEWS.d/next/Core_and_Builtins/2026-10-19-19-33-35.gh-issue-159739.09590b.rst
new file mode 100644
index 00000000000000..3231be417aa80e
--- /dev/null
+++ b/Misc/NEWS.d/next/Core_and_Builtins/2026-10-19-19-33-35.gh-issue-159739.09590b.rst
@@ -0,0 +1 @@
+Avoid a crash when a module filename cannot be encoded as UTF-8.
diff --git a/Objects/moduleobject.c b/Objects/moduleobject.c
index 162a43c18bce72..5c0d11b1784ef6 100644
--- a/Objects/moduleobject.c
+++ b/Objects/moduleobject.c
@@ -686,6 +686,10 @@ _PyModule_GetFilenameUTF8(PyObject *mod, char *buffer, Py_ssize_t maxlen)
     }
     else {
         const char *filename = PyUnicode_AsUTF8AndSize(filenameobj, &size);
+        if (filename == NULL) {
+            Py_DECREF(filenameobj);
+            return -1;
+        }
         assert(size >= 0);
         if (size > maxlen) {
             size = -1;