diff --git a/libmwaw.spec b/libmwaw.spec
index f237975..7d2065f 100644
--- a/libmwaw.spec
+++ b/libmwaw.spec
@@ -48,7 +48,7 @@ Supported output formats are CSV, HTML, SVG, plain text and raw.
 %autosetup -p1
 
 %build
-export CXXFLAGS=-std=c++11
+export CXXFLAGS="-std=c++11 %{optflags}"
 %configure --disable-static --disable-werror --disable-zip --enable-docs --with-sharedptr=c++11
 sed -i \
     -e 's|^hardcode_libdir_flag_spec=.*|hardcode_libdir_flag_spec=""|g' \