diff --git a/make/projects-dir.mk b/make/projects-dir.mk
index 944b2997..fc9010ba 100644
--- a/make/projects-dir.mk
+++ b/make/projects-dir.mk
@@ -183,13 +183,13 @@ build-order-%: $(filter-out $(UNAVAILABLE_TARGETS),pull.done)
 build-order: build-order-all
 
 echo-build-deps:
-	$(Q)$(JW_PKG_PY_PROJECTS) required-os-pkg --quote --skip-excluded --flavours "build" $(TARGET_PROJECTS)
+	$(Q)$(JW_PKG_PY_PROJECTS) required-os-pkg --quote --skip-excluded "build" $(TARGET_PROJECTS)
 
 echo-install-deps:
-	$(Q)$(JW_PKG_PY_PROJECTS) required-os-pkg --quote --skip-excluded --flavours "build run" $(TARGET_PROJECTS)
+	$(Q)$(JW_PKG_PY_PROJECTS) required-os-pkg --quote --skip-excluded "build,run" $(TARGET_PROJECTS)
 
 echo-release-deps:
-	$(Q)$(JW_PKG_PY_PROJECTS) required-os-pkg --quote --skip-excluded --flavours "build run release" $(TARGET_PROJECTS)
+	$(Q)$(JW_PKG_PY_PROJECTS) required-os-pkg --quote --skip-excluded "build,run,release" $(TARGET_PROJECTS)
 echo-os:
 	$(Q)$(JW_PKG_PY) distro info
 
@@ -246,10 +246,10 @@ pkg-manager-dup:
 	$(PKG_MANAGER) dup
 
 pkg-install-build-deps:
-	$(PKG_MANAGER) install $(shell $(JW_PKG_PY_PROJECTS) required-os-pkg --quote --skip-excluded --flavours build $(TARGET_PROJECTS))
+	$(PKG_MANAGER) install $(shell $(JW_PKG_PY_PROJECTS) required-os-pkg --quote --skip-excluded "build" $(TARGET_PROJECTS))
 
 pkg-install-release-deps:
-	$(PKG_MANAGER) install $(shell $(JW_PKG_PY_PROJECTS) required-os-pkg --quote --skip-excluded --flavours 'build run release' $(TARGET_PROJECTS))
+	$(PKG_MANAGER) install $(shell $(JW_PKG_PY_PROJECTS) required-os-pkg --quote --skip-excluded "build,run,release" $(TARGET_PROJECTS))
 
 pkg-release-reinstall: $(PREREQ_RELEASE)
 
diff --git a/make/topdir.mk b/make/topdir.mk
index cb2a01ef..0020129a 100644
--- a/make/topdir.mk
+++ b/make/topdir.mk
@@ -193,7 +193,7 @@ prefix.done:
 	touch $@
 
 echo-build-deps:
-	$(Q)echo $(call proj_query, required-os-pkg --quote --flavours "build" $(PROJECT))
+	$(Q)echo $(call proj_query, required-os-pkg --quote "build" $(PROJECT))
 
 git-ssh-%:
 	bash -c "`git remote get-url --push $* | sed 's|ssh://||; s|\([^/]\+\)/\(.*\)|LC_CDPATH=/\2 ssh -o SendEnv=LC_CDPATH \1|'`"
@@ -215,10 +215,10 @@ pkg-manager-refresh:
 	$(PKG_MANAGER) refresh
 
 pkg-install-build-deps:
-	$(PKG_MANAGER) install $(shell $(proj_query_cmd) required-os-pkg --quote --skip-excluded --flavours "build" $(PROJECT))
+	$(PKG_MANAGER) install $(shell $(proj_query_cmd) required-os-pkg --quote --skip-excluded "build" $(PROJECT))
 
 pkg-install-release-deps:
-	$(PKG_MANAGER) install $(shell $(proj_query_cmd) required-os-pkg --quote --skip-excluded --flavours "build run release" $(PROJECT))
+	$(PKG_MANAGER) install $(shell $(proj_query_cmd) required-os-pkg --quote --skip-excluded "build,run,release" $(PROJECT))
 
 pkg-install-testbuild-deps: pkg-install-release-deps
 
diff --git a/src/python/jw/pkg/cmds/projects/CmdRequiredOsPkg.py b/src/python/jw/pkg/cmds/projects/CmdRequiredOsPkg.py
index 5217412a..8d282c2c 100644
--- a/src/python/jw/pkg/cmds/projects/CmdRequiredOsPkg.py
+++ b/src/python/jw/pkg/cmds/projects/CmdRequiredOsPkg.py
@@ -16,16 +16,16 @@ class CmdRequiredOsPkg(Cmd): # export
 
     def add_arguments(self, parser: ArgumentParser) -> None:
         super().add_arguments(parser)
-        parser.add_argument('module', nargs='*', help='Modules')
-        parser.add_argument('--flavours', help='Dependency flavours', default='build')
+        parser.add_argument('flavours', help='Dependency flavours', default='build')
+        parser.add_argument('modules', nargs='*', help='Modules')
         parser.add_argument('--skip-excluded', action='store_true', default=False,
-            help='Output empty prerequisite list if module is excluded')
+            help='Output empty prerequisite list for excluded modules')
         parser.add_argument('--quote', action='store_true', default=False,
             help='Put double quotes around each listed dependency')
 
     async def _run(self, args: Namespace) -> None:
-        modules = args.module
-        flavours = set(args.flavours.split())
+        modules = args.modules
+        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.add('run')