diff --git a/src/python/jw/pkg/cmds/projects/CmdBuild.py b/src/python/jw/pkg/cmds/projects/CmdBuild.py
index ca8c8bf7..3c83ad83 100644
--- a/src/python/jw/pkg/cmds/projects/CmdBuild.py
+++ b/src/python/jw/pkg/cmds/projects/CmdBuild.py
@@ -112,7 +112,7 @@ class CmdBuild(Cmd):  # export
             return ret
 
         def add_dep_tree(cur, prereq_types, tree, all_deps):
-            log(DEBUG, 'Adding deps "{" ".join(prereq_types)}" of module {cur)')
+            log(DEBUG, f'Adding deps "{" ".join(prereq_types)}" of module {cur}')
             if cur in all_deps:
                 log(DEBUG, 'Already handled module "{cur}"')
                 return 0