diff --git a/src/template/solaris b/src/template/solaris
index 07c79e9067eb589d6571cb47663fe64d2211549d..6114c3c1c8ff8a484c6bc0d0f1cd246e63524f0c 100644
--- a/src/template/solaris
+++ b/src/template/solaris
@@ -10,6 +10,7 @@ case $host in
 esac
 
 # tools/thread/thread_test must be run
+# -D_POSIX_PTHREAD_SEMANTICS enables 5-arg getpwuid_r, among other things
 if test "$GCC" = yes 
 then	THREAD_CPPFLAGS="-D_POSIX_PTHREAD_SEMANTICS"
 	THREAD_LIBS="-pthread"