diff --git a/README.md b/README.md
index a031fbc14..5e9587d2d 100644
--- a/README.md
+++ b/README.md
@@ -256,3 +256,20 @@ First, build and run the host tests as usual (see above).
     $ genhtml -o covreport coverage.info # or lcov --list coverage.info
 
 The coverage report is now available at `covreport/index.html`.
+
+
+LP32 ABI bugs
+-------------
+
+This probably belongs in the NDK documentation rather than here, but these
+are the known ABI bugs in LP32:
+
+ * time_t is 32-bit. http://b/5819737
+
+ * off_t is 32-bit. There is off64_t, but no _FILE_OFFSET_BITS support.
+   Many of the off64_t functions are missing in older releases, and
+   stdio uses 32-bit offsets, so there's no way to fully implement
+   _FILE_OFFSET_BITS.
+
+ * sigset_t is too small on ARM and x86 (but correct on MIPS), so support
+   for real-time signals is broken. http://b/5828899