diff -up mutt-1.5.21/crypt-gpgme.c.notation mutt-1.5.21/crypt-gpgme.c
--- mutt-1.5.21/crypt-gpgme.c.notation 2012-04-25 10:26:20.589226791 +0200
+++ mutt-1.5.21/crypt-gpgme.c 2012-04-25 10:28:02.075915855 +0200
@@ -72,7 +72,8 @@
#define xtoi_2(p) ((xtoi_1(p) * 16) + xtoi_1((p)+1))
#define PKA_NOTATION_NAME "pka-address@gnupg.org"
-#define is_pka_notation(notation) (! strcmp ((notation)->name, \
+#define is_pka_notation(notation) ((notation)->name && \
+ ! strcmp ((notation)->name, \
PKA_NOTATION_NAME))
/* Values used for comparing addresses. */