diff --git a/rpy.spec b/rpy.spec
index 6552f2c..dc66454 100644
--- a/rpy.spec
+++ b/rpy.spec
@@ -55,12 +55,13 @@ converted to Python exceptions.
 %setup -q -n %{srcname}2-%{version}
 
 %build
+# %py2_build
+# %py3_build
+
 # Temporary workaround to fix a bug in R
 # see https://stat.ethz.ch/pipermail/r-devel/2016-December/073548.html
-export CFLAGS+=" -DHAVE_UINTPTR_T=1"
-
-%py2_build
-%py3_build
+CFLAGS="$RPM_OPT_FLAGS -DHAVE_UINTPTR_T=1" %{__python2} setup.py build
+CFLAGS="$RPM_OPT_FLAGS -DHAVE_UINTPTR_T=1" %{__python3} setup.py build
 
 %install
 %py2_install
@@ -80,7 +81,7 @@ export CFLAGS+=" -DHAVE_UINTPTR_T=1"
 %changelog
 * Fri Dec 30 2016 José Matos <jamatos@fedoraproject.org> - 2.8.5-1
 - update to 2.8.5
-- workaround to fix a bug in R
+- workaround to fix a bug in R (it fails for 32 bit archs)
 
 * Mon Dec 19 2016 Miro Hrončok <mhroncok@redhat.com> - 2.8.3-2
 - Rebuild for Python 3.6