properly export the .so minor version
diff --git a/CMakeLists.txt b/CMakeLists.txt
index 11e350f..8e9e315 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -34,7 +34,7 @@
     PACKAGE_VERSION_PATCH
 )
 
-set (PACKAGE_SOVERSION "${PACKAGE_VERSION_MAJOR}")
+set (PACKAGE_SOVERSION "${PACKAGE_VERSION_MAJOR}.${PACKAGE_VERSION_MINOR}")
 
 # ----------------------------------------------------------------------------
 # options