diff --git a/src/cso/__init__.py b/src/cso/__init__.py
index 401f8b064a7d893842ebd44f2eeaadbf3776fc94..566cc862b44fdec517075d2c4eacc9be09dbaf69 100644
--- a/src/cso/__init__.py
+++ b/src/cso/__init__.py
@@ -108,9 +108,20 @@ and are defined according to the following hierchy:
 # -------------------------------------------------
 
 # store version number:
-from importlib import metadata
-
-__version__ = metadata.version(__package__)
+try:
+    from importlib import metadata
+    __version__ = metadata.version(__package__)
+except:
+    import os
+    if "CSO_PREFIX" in os.environ.keys():
+        import tomllib
+        with open(os.path.join(os.environ["CSO_PREFIX"],"pyproject.toml"),"rb") as f :
+            pp = tomllib.load( f )
+        __version__ = pp["project"]["version"]
+    else:
+        __version__ = "x.y"
+    #endif
+#endtry
 
 # import entities from sub-modules:
 from .cso_file import *