diff --git a/Makefile.am b/Makefile.am
index be6c312..4836c6a 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -37,7 +37,7 @@ pam_yubico_la_SOURCES = pam_yubico.c
 pam_yubico_la_LIBADD = @LTLIBYKCLIENT@ @LIBLDAP@
 pam_yubico_la_LDFLAGS = -module -avoid-version
 
-DEFS = -DDEBUG_PAM @DEFS@
+DEFS = -DDEBUG_PAM -DPAM_DEBUG @DEFS@
 
 # Self tests.
 
diff --git a/NEWS b/NEWS
index a8e0e3c..2b95b2c 100644
--- a/NEWS
+++ b/NEWS
@@ -6,6 +6,10 @@ pam_yubico NEWS -- History of user-visible changes.             -*- outline -*-
 Contributed by qistoph reported in Issue #22:
 <http://code.google.com/p/yubico-pam/issues/detail?id=22>.
 
+** Build with -DPAM_DEBUG so that debug file writing works.
+Reported by qistoph in Issue #20:
+<http://code.google.com/p/yubico-pam/issues/detail?id=20>.
+
 * Version 2.3 (released 2010-04-14)
 
 ** New keyword "ldap_uri" added.