diff --git a/static/js/graphing.js b/static/js/graphing.js
index 65a11a265..c65af00b5 100644
--- a/static/js/graphing.js
+++ b/static/js/graphing.js
@@ -340,6 +340,23 @@ ImageHistoryTree.prototype.changeImage_ = function(imageId) {
 };
 
 
+/**
+ * Expands the given collapsed node in the tree.
+ */
+ImageHistoryTree.prototype.expandCollapsed_ = function(imageNode) {
+  var index = imageNode.parent.children.indexOf(imageNode);
+  if (index < 0 || imageNode.encountered.length < 2) {
+    return;
+  }
+
+  // Note: we start at 1 since the 0th encountered node is the parent.
+  imageNode.parent.children.splice(index, 1, imageNode.encountered[1]);
+  this.maxHeight_ = this.determineMaximumHeight_(this.root_);
+  this.update_(this.root_);
+  this.updateDimensions_();
+};
+
+
 /**
  * Builds the root node for the tree.
  */
@@ -642,7 +659,10 @@ ImageHistoryTree.prototype.update_ = function(source) {
     .attr("dy", ".35em")
     .attr("text-anchor", function(d) { return d.children || d._children ? "end" : "start"; })
     .text(function(d) { return d.name; })
-    .on("click", function(d) { if (d.image) { that.changeImage_(d.image.id); } })
+    .on("click", function(d) {
+      if (d.image) { that.changeImage_(d.image.id); }
+      if (d.collapsed) { that.expandCollapsed_(d); }
+    })
     .on('mouseover', tip.show)
     .on('mouseout', tip.hide);
 
@@ -695,9 +715,9 @@ ImageHistoryTree.prototype.update_ = function(source) {
       if (d.virtual) {
         return 'virtual';
       }
-	    if (!currentImage) {
-	      return '';
-	    }
+      if (!currentImage) {
+	return '';
+      }
       return d.image.id == currentImage.id ? 'current' : '';
     });