diff --git a/src/libiso8601/build.install-lib b/src/libiso8601/build.install-lib
index 94d4460..3768c51 100644
--- a/src/libiso8601/build.install-lib
+++ b/src/libiso8601/build.install-lib
@@ -7,6 +7,7 @@ build_dir_tree "${INCLUDEDIR}" || return 1
 
 # install library
 echo "Installing libraries into '${LIBDIR}'"
+source src/libiso8601/soversion
 install_file ${libiso8601} ${LIBDIR} 0755 || return 1
 BASE="${libiso8601_BASE}.so"
 MAJOR="${BASE}.${SOMAJOR}"