diff --git a/spack.spec b/spack.spec
index b812bde..5b6226a 100644
--- a/spack.spec
+++ b/spack.spec
@@ -126,7 +126,7 @@ BuildRequires:  makeinfo
 # Hardcode this - there is no python2 version of this around any more.
 BuildRequires:  %{mypython}-Sphinx >= 3.4
 BuildRequires:  %{mypython}-sphinxcontrib-programoutput
-BuildRequires:  spack
+BuildRequires:  spack = %version
 # html
 BuildRequires:  graphviz
 # info