Issue #10833: Use PyUnicode_FromFormat() and PyErr_Format() instead of
PyOS_snprintf().
diff --git a/Modules/_testcapimodule.c b/Modules/_testcapimodule.c
index f19d0df..75dbe57 100644
--- a/Modules/_testcapimodule.c
+++ b/Modules/_testcapimodule.c
@@ -43,11 +43,9 @@
 sizeof_error(const char* fatname, const char* typname,
     int expected, int got)
 {
-    char buf[1024];
-    PyOS_snprintf(buf, sizeof(buf),
-        "%.200s #define == %d but sizeof(%.200s) == %d",
+    PyErr_Format(TestError,
+        "%s #define == %d but sizeof(%s) == %d",
         fatname, expected, typname, got);
-    PyErr_SetString(TestError, buf);
     return (PyObject*)NULL;
 }