diff --git a/lapack.spec b/lapack.spec
index 7f1a908..6775172 100644
--- a/lapack.spec
+++ b/lapack.spec
@@ -1,7 +1,7 @@
 %global shortver	3
 %global mediumver	%{shortver}.5
 
-%if %{__isa_bits} == 64
+%if %{?__isa_bits:%{__isa_bits}}%{!?__isa_bits:32} == 64
 %global arch64 1
 %else
 %global arch64 0
@@ -463,6 +463,7 @@ ln -sf libblas64.so.%{version} libblas64.so.%{mediumver}
 * Fri Sep 11 2015 Tom Callaway <spot@fedoraproject.org> - 3.5.0-12
 - fix missing dependencies between subpackages
 - delete broken and wrongly installed manpages
+- fix isa_bits conditional
 
 * Wed Jun 17 2015 Fedora Release Engineering <rel-eng@lists.fedoraproject.org> - 3.5.0-11
 - Rebuilt for https://fedoraproject.org/wiki/Fedora_23_Mass_Rebuild