diff --git a/libc/malloc_debug/README_marshmallow_and_earlier.md b/libc/malloc_debug/README_marshmallow_and_earlier.md
index 3513711..c8be656 100644
--- a/libc/malloc_debug/README_marshmallow_and_earlier.md
+++ b/libc/malloc_debug/README_marshmallow_and_earlier.md
@@ -4,10 +4,10 @@
 Malloc debug is a method of debugging native memory problems. It can help
 detect memory corruption, memory leaks, and use after free issues.
 
-This documentation describes how to enable this feature on versions of
-the Android OS, Marshmallow or older. Note: malloc debug was full of bugs
-and was not fully functional until KitKat, so using it on a version older
-than that is not guaranteed to work at all.
+This documentation describes how to enable this feature on API level
+23 or older. Note: malloc debug was full of bugs and was not fully
+functional until API level 19, so using it on a version older than that
+is not guaranteed to work at all.
 
 The documentation for malloc debug on newer versions of Android is
 [here](README.md).
diff --git a/libc/stdio/local.h b/libc/stdio/local.h
index 517935b..a31d7b9 100644
--- a/libc/stdio/local.h
+++ b/libc/stdio/local.h
@@ -166,11 +166,10 @@
     _EXT(fp)->_caller_handles_locking = true; \
   } while (0)
 
-/*
- * Android <= KitKat had getc/putc macros in <stdio.h> that referred
- * to __srget/__swbuf, so those symbols need to be public for LP32
- * but can be hidden for LP64.
- */
+// Android <= 19 had getc/putc macros in <stdio.h> that referred
+// to __srget/__swbuf, so those symbols need to be public for LP32
+// but can be hidden for LP64. Moreover, the NDK continued to ship
+// those macros until r15 made unified headers the default.
 __LIBC32_LEGACY_PUBLIC__ int __srget(FILE*);
 __LIBC32_LEGACY_PUBLIC__ int __swbuf(int, FILE*);
 __LIBC32_LEGACY_PUBLIC__ int __srefill(FILE*);