diff --git a/perftest.spec b/perftest.spec
index 061c779..4cf3a42 100644
--- a/perftest.spec
+++ b/perftest.spec
@@ -2,6 +2,8 @@ Name:           perftest
 Summary:        IB Performance Tests
 # Upstream uses a dash in the version. Not valid in the Version field, so we use a dot instead.
 %global upstream_ver 4.5-0.20
+# The directory in the tarball has only the part before the dash.
+%global tarball_ver 4.5
 Version:        4.5.0.20
 Release:        %autorelease
 License:        GPLv2 or BSD
@@ -24,7 +26,7 @@ connections.  It does not work on normal TCP/IP networks, only on
 RDMA networks.
 
 %prep
-%setup -q
+%setup -q -n %{name}-%{tarball_ver}
 find src -type f -iname '*.[ch]' -exec chmod a-x '{}' ';'
 
 %build