diff --git a/dovecot.spec b/dovecot.spec
index bdb4559..4ce79ea 100644
--- a/dovecot.spec
+++ b/dovecot.spec
@@ -54,7 +54,7 @@ BuildRequires: libtool
 BuildRequires: autoconf
 BuildRequires: automake
 BuildRequires: krb5-devel
-BuildRequires: byacc
+BuildRequires: byacc, bison, flex
 # gettext-devel is needed for running autoconf because of the
 # presence of AM_ICONV
 BuildRequires: gettext-devel