diff --git a/libc/stdio/local.h b/libc/stdio/local.h
index 1ecf122..12f3bf5 100644
--- a/libc/stdio/local.h
+++ b/libc/stdio/local.h
@@ -259,7 +259,7 @@
 size_t parsefloat(FILE*, char*, char*);
 size_t wparsefloat(FILE*, wchar_t*, wchar_t*);
 
-// Sanity check a FILE* for nullptr, so we can emit a message while crashing
+// Check a FILE* isn't nullptr, so we can emit a message while crashing
 // instead of doing a blind null-dereference.
 #define CHECK_FP(fp) \
   if (fp == nullptr) __fortify_fatal("%s: null FILE*", __FUNCTION__)
diff --git a/libc/stdio/stdio.cpp b/libc/stdio/stdio.cpp
index a0b4219..afc2c48 100644
--- a/libc/stdio/stdio.cpp
+++ b/libc/stdio/stdio.cpp
@@ -1026,9 +1026,9 @@
   __check_count("vsnprintf", "size", n);
 
   // Stdio internals do not deal correctly with zero length buffer.
-  char dummy;
+  char one_byte_buffer[1];
   if (n == 0) {
-    s = &dummy;
+    s = one_byte_buffer;
     n = 1;
   }