diff --git a/unison.spec b/unison.spec
index f91c754..2aa2809 100644
--- a/unison.spec
+++ b/unison.spec
@@ -79,7 +79,7 @@ replica to the other.
 
 %build
 %if "%build_flavor" == "doc"
-%make_build docs
+%make_build docs -j1
 ls -lart doc man
 %else
 dune_release_pkgs='unison,unison-gui,unison-fsmonitor'