$ make
Scanning dependencies of target clusters
[ 12%] Building CXX object CMakeFiles/clusters.dir/clusters.cc.o
[ 25%] Building CXX object CMakeFiles/clusters.dir/util.cc.o
Linking CXX static library libclusters.a
[ 25%] Built target clusters
Scanning dependencies of target fileseverity
[ 37%] Building CXX object CMakeFiles/fileseverity.dir/fileseverity.cc.o
Linking CXX executable fileseverity
libclusters.a(clusters.cc.o): In function `Clusters::collect_fragments(Glib::ustring const&)':
clusters.cc:(.text+0x16e2): undefined reference to `Glib::ustring::c_str() const'
clusters.cc:(.text+0x1ae9): undefined reference to `Glib::ustring::c_str() const'
collect2: ld returned 1 exit status
make[2]: *** [fileseverity] Error 1
make[1]: *** [CMakeFiles/fileseverity.dir/all] Error 2
make: *** [all] Error 2