diff --git a/bc.spec b/bc.spec
index af1cb99..90d28db 100644
--- a/bc.spec
+++ b/bc.spec
@@ -11,7 +11,7 @@ Patch2: bc-1.06.95-memleak.patch
 Requires(post): /sbin/install-info
 Requires(preun): /sbin/install-info
 Buildroot: %{_tmppath}/%{name}-%{version}-%{release}-root-%(%{__id_u} -n)
-BuildRequires: readline-devel, flex
+BuildRequires: readline-devel, flex, bison
 
 %description
 The bc package includes bc and dc. Bc is an arbitrary precision