diff --git a/lib/Babble/Plugin/CoreSignatures.pm b/lib/Babble/Plugin/CoreSignatures.pm
index a93160d..b36f44b 100644
--- a/lib/Babble/Plugin/CoreSignatures.pm
+++ b/lib/Babble/Plugin/CoreSignatures.pm
@@ -93,7 +93,10 @@ sub transform_to_plain {
       push @sig_text, $part;
     }
 
-    my $sig_text = 'my ('.(join ', ', @sig_text).') = @_;';
+    my $sig_text =
+      @sig_text
+      ? 'my ('.(join ', ', @sig_text).') = @_;'
+      : '';
     my $code = join ' ', $sig_text, @defaults;
     $s->{body}->transform_text(sub { s/^{/{ ${code}/ });
     if ($proto) {
diff --git a/t/plugin-coresignatures.t b/t/plugin-coresignatures.t
index 9add7eb..3fb0d94 100644
--- a/t/plugin-coresignatures.t
+++ b/t/plugin-coresignatures.t
@@ -57,10 +57,16 @@ my @cand = (
     'sub foo ($) { my ($sig) = @_; }', ],
   [ 'sub foo :Foo :prototype($) ($sig) { }',
     'sub foo ($) :Foo { my ($sig) = @_; }', ],
+
   [ 'sub foo : Foo prototype($) ($sig) { }',
     'sub foo ($) : Foo { my ($sig) = @_; }', ],
   [ 'sub foo :prototype($) Foo ($sig) { }',
     'sub foo ($) :Foo { my ($sig) = @_; }', ],
+
+  [ 'sub foo : Foo prototype($) () { }',
+    'sub foo ($) : Foo {  }', ],
+  [ 'sub foo :prototype($) Foo () { }',
+    'sub foo ($) :Foo {  }', ],
   [ 'use Mojo::Base -base, -signatures;',
     'use Mojo::Base qw(-base);' ],
   [ 'use Mojo::Base -signatures;',