diff --git a/make/disabled.mk b/make/disabled.mk
new file mode 100644
index 00000000..2b6558c8
--- /dev/null
+++ b/make/disabled.mk
@@ -0,0 +1,7 @@
+DISABLED = @echo Target \"$1\" in $(shell pwd)/Makefile has been disabled.
+
+all:
+	$(call DISABLED,$@)
+
+install clean distclean:
+	$(call DISABLED,$@)
diff --git a/src/python/jw/pkg/cmds/projects/CmdBuild.py b/src/python/jw/pkg/cmds/projects/CmdBuild.py
index 6677e71b..09f71122 100644
--- a/src/python/jw/pkg/cmds/projects/CmdBuild.py
+++ b/src/python/jw/pkg/cmds/projects/CmdBuild.py
@@ -283,7 +283,29 @@ class CmdBuild(Cmd):  # export
                 log(NOTICE, 'Using prerequisite flavours ' + ' '.join(dep_flavours))
                 log(NOTICE, 'Calculating order for modules ... ')
 
-            calculate_order(order, modules, dep_flavours)
+            def is_makefile_only(m: str) -> bool:
+                # Not installed as a package (no project.conf, no VERSION),
+                # but a project directory with a Makefile in the workspace:
+                # buildable with a plain make, no jw dependencies to read.
+                if self.app.is_installed(m, devel = True) \
+                        or self.app.is_installed(m, devel = False):
+                    return False
+                try:
+                    wd = proj_dir(m)
+                except Exception:
+                    return False
+                return wd is not None and os.path.exists(f'{wd}/Makefile')
+
+            makefile_only = {m for m in modules if is_makefile_only(m)}
+            for m in sorted(makefile_only):
+                log(
+                    NOTICE,
+                    f'Project {m} is not installed, building it as a plain '
+                    f'Makefile project'
+                )
+            calculate_order(order, modules - makefile_only, dep_flavours)
+            for m in sorted(makefile_only):
+                order.append(m)
             if args.ignore_deps:
                 order = [m for m in order if m in args.modules]
             order = [m for m in order if m not in exclude]