diff --git a/src/allmydata/scripts/cli.py b/src/allmydata/scripts/cli.py
index 722c8d983..b7dfb2e3c 100644
--- a/src/allmydata/scripts/cli.py
+++ b/src/allmydata/scripts/cli.py
@@ -82,6 +82,9 @@ class CreateAliasOptions(FilesystemOptions):
 class ListAliasesOptions(FilesystemOptions):
     synopsis = "[options]"
     description = """Display a table of all configured aliases."""
+    optFlags = [
+        ("readonly-uri", None, "Show read-only dircaps instead of readwrite"),
+    ]
 
 class ListOptions(FilesystemOptions):
     optFlags = [
diff --git a/src/allmydata/scripts/tahoe_add_alias.py b/src/allmydata/scripts/tahoe_add_alias.py
index 30794429e..eb91fff61 100644
--- a/src/allmydata/scripts/tahoe_add_alias.py
+++ b/src/allmydata/scripts/tahoe_add_alias.py
@@ -105,8 +105,11 @@ def list_aliases(options):
     fmt = "%" + str(max_width) + "s: %s"
     rc = 0
     for name in alias_names:
+        dircap = uri.from_string(aliases[name])
+        if options['readonly-uri']:
+            dircap = dircap.get_readonly()
         try:
-            print >>stdout, fmt % (unicode_to_output(name), unicode_to_output(aliases[name].decode('utf-8')))
+            print >>stdout, fmt % (unicode_to_output(name), unicode_to_output(dircap.to_string().decode('utf-8')))
         except (UnicodeEncodeError, UnicodeDecodeError):
             print >>stderr, fmt % (quote_output(name), quote_output(aliases[name]))
             rc = 1