Index: python-pweave/pweave/__init__.py
===================================================================
--- python-pweave.orig/pweave/__init__.py	2023-01-31 13:02:12.658424192 +0100
+++ python-pweave/pweave/__init__.py	2023-01-31 13:57:06.769361665 +0100
@@ -44,7 +44,7 @@
     if figformat is not None:
         sys.stdout.write("figformat option is not implemented for Pweave >= 0.3")
 
-    assert file != "" is not None, "No input specified"
+    assert file is not None and file != "", "No input specified"
 
     doc = Pweb(file, informat=informat, doctype=doctype,
                kernel=kernel, output=output, figdir=figdir,