diff --git a/lib/redmine/views/labelled_form_builder.rb b/lib/redmine/views/labelled_form_builder.rb
index 8c97b8215..f364ca8e2 100644
--- a/lib/redmine/views/labelled_form_builder.rb
+++ b/lib/redmine/views/labelled_form_builder.rb
@@ -49,6 +49,7 @@ class Redmine::Views::LabelledFormBuilder < ActionView::Helpers::FormBuilder
     # display the value before type cast when the entered value is not valid
     if @object.errors[field].blank?
       options = options.merge(:value => format_hours(@object.send field))
+                       .with_defaults(:placeholder => 'h:mm')
     end
     text_field field, options
   end
diff --git a/test/unit/lib/redmine/views/labelled_form_builder_test.rb b/test/unit/lib/redmine/views/labelled_form_builder_test.rb
index e7701c4bc..aa79a3b43 100644
--- a/test/unit/lib/redmine/views/labelled_form_builder_test.rb
+++ b/test/unit/lib/redmine/views/labelled_form_builder_test.rb
@@ -35,7 +35,9 @@ class Redmine::Views::LabelledFormBuilderTest < Redmine::HelperTest
     entry.validate
 
     labelled_form_for(entry) do |f|
-      assert_include 'value="2:30"', f.hours_field(:hours)
+      field_html = f.hours_field(:hours)
+      assert_include 'value="2:30"', field_html
+      assert_include 'placeholder="h:mm"', field_html
     end
   end