diff --git a/docs/known-issues.txt b/docs/known-issues.txt
index 54d9de3b..fd367ae6 100644
--- a/docs/known-issues.txt
+++ b/docs/known-issues.txt
@@ -2,4 +2,17 @@ Glibc does not build: asm/page.h not found
 
 As of linux-2.6.25, asm/page.h is no longer exported.
 This means the glibc up to and including 2.6.1 will not build against headers
-exported from linux-2.6.25 and up. Status of glibc 2.7 and above is unknown.
+exported from linux-2.6.25 and up. Status of glibc-2.7 and above is unknown.
+
+----
+dmalloc does not build
+
+This broken build has been observed for big endian ARm with glibc and NPTL,
+and with i686 with glibc and NPTL.
+
+This has not been fully investigated yet. There is a name clash with strdup,
+where it is a macro somewhere, and dmalloc tries to re-declare a strdup
+function in dmalloc.h, but the declaration is overwritten with the macro
+expansion, and thus the build is broken.
+
+The common denominator seems to be NPTL.