diff --git a/CHANGELOG.txt b/CHANGELOG.txt
index 7a45e1013668a7859fa1849d0ba8ee9ab7d8f575..816f5290887f6119c50ca1d08a07560da36a5555 100644
--- a/CHANGELOG.txt
+++ b/CHANGELOG.txt
@@ -31,6 +31,7 @@ Add a couple of support functions for ctools_set_page_token that are meant to be
 #424548: Add a warning about overridng pager settings with Views AJAX.
 #555802: Add an administrative title to custom content panes to make them easier to manage.
 #556870: Node edit settings form context autocomplete was not working correctly.
+#491884 by ayalon: Provide blank substitutions for optional contexts that do not appear.
 
 ctools 6.x-1.0
 ==============
diff --git a/includes/context.inc b/includes/context.inc
index c1ff54861f1b970259dbd5385d443f6f388e5b09..ac450ec33a959a20ce7134eb029e4d99fd7a26f8 100644
--- a/includes/context.inc
+++ b/includes/context.inc
@@ -613,6 +613,9 @@ function ctools_context_keyword_substitute($string, $keywords, $contexts) {
         if (isset($context_keywords[$context])) {
           $keywords['%' . $keyword] = ctools_context_convert_context($context_keywords[$context], $converter);
         }
+        else {
+          $keywords['%' . $keyword] = '';
+        }
       }
       else {
         if (isset($context_keywords[$keyword])) {