diff --git a/.abf.yml b/.abf.yml
index 4b4250a..c522926 100644
--- a/.abf.yml
+++ b/.abf.yml
@@ -1,2 +1,2 @@
 sources:
-  upx-3.09-src.tar.bz2: df474a9909e6697a4d3240767c34e2dcb39002c1
+  upx-3.91-src.tar.bz2: da962c0affb27eae11aa9b6fbd751c3699717b36
diff --git a/upx.spec b/upx.spec
index 6c000dc..5155150 100644
--- a/upx.spec
+++ b/upx.spec
@@ -1,7 +1,7 @@
 Summary:	The Ultimate Packer for eXecutables
 Name:		upx
-Version:	3.09
-Release:	2
+Version:	3.91
+Release:	3
 License:	GPLv2+
 Group:		Archiving/Compression
 URL:		http://upx.sourceforge.net/
@@ -39,7 +39,7 @@ http://compression.ca/act-exepack.html
 # building the docs
 %make -C doc
 export UCLDIR=%{_prefix}
-%make -C src CXXFLAGS="%{optflags} -Wcast-align -Wcast-qual -Wpointer-arith -Wwrite-strings"
+%make -C src CXXFLAGS="%{optflags} -Wcast-align -Wcast-qual -Wpointer-arith -Wwrite-strings" CXX="%__cxx"
 
 %install
 install -d %{buildroot}%{_bindir}