diff --git a/src/python/jw/pkg/cmds/projects/CmdRequiredOsPkg.py b/src/python/jw/pkg/cmds/projects/CmdRequiredOsPkg.py
index 28e8b21a..5217412a 100644
--- a/src/python/jw/pkg/cmds/projects/CmdRequiredOsPkg.py
+++ b/src/python/jw/pkg/cmds/projects/CmdRequiredOsPkg.py
@@ -25,10 +25,12 @@ class CmdRequiredOsPkg(Cmd): # export
 
     async def _run(self, args: Namespace) -> None:
         modules = args.module
-        flavours = args.flavours.split()
-        if 'build' in flavours and not 'run' in flavours:
+        flavours = set(args.flavours.split())
+        if 'build' in flavours:
             # TODO: This adds too much. Only the run dependencies of the build dependencies would be needed.
-            flavours.append('run')
+            flavours.add('run')
+        if 'release' in flavours:
+            flavours |= set(['run', 'devel', 'build'])
         log(DEBUG, "flavours = " + args.flavours)
         deps = self.app.get_project_refs(modules, ['pkg.requires.jw'], flavours,
                 scope = Scope.Subtree, add_self=True, names_only=True)
@@ -38,12 +40,12 @@ class CmdRequiredOsPkg(Cmd): # export
                     deps.remove(d)
         subsecs = self.app.os_cascade()
         log(DEBUG, "subsecs = ", subsecs)
-        requires = []
+        requires: set[str] = set()
         for sec in subsecs:
             for flavour in flavours:
                 vals = self.app.get_values(deps, ['pkg.requires.' + sec], [flavour])
                 if vals:
-                    requires = requires + vals
+                    requires |= set(vals)
         if args.quote:
             requires = [f'"{dep}"' for dep in requires]
         # TODO: add all not in build tree as -devel