diff --git a/examples/serialized_custom_source/serialized_source_ring.cpp b/examples/serialized_custom_source/serialized_source_ring.cpp
index 560a99345..7e19bc579 100644
--- a/examples/serialized_custom_source/serialized_source_ring.cpp
+++ b/examples/serialized_custom_source/serialized_source_ring.cpp
@@ -23,9 +23,11 @@ class SerialisedSource {
 
     // The deserialisation routine populates the constructor from well defined elements
     // in the input XML document.
+    // Note that the source will have already been read from file, so what will be passed
+    // in here is a string-like serialized value (not the path to the serialized value).
     static SerialisedSource from_xml(char* serialised_source) {
       pugi::xml_document doc;
-      doc.load_file(serialised_source);
+      doc.load_string(serialised_source);
       pugi::xml_node root_node = doc.root().child("Source");
       double radius = root_node.child("Radius").text().as_double();
       double energy = root_node.child("Energy").text().as_double();
diff --git a/src/source.cpp b/src/source.cpp
index 86dac6b3f..d7bcf726b 100644
--- a/src/source.cpp
+++ b/src/source.cpp
@@ -99,7 +99,13 @@ SourceDistribution::SourceDistribution(pugi::xml_node node)
     }
 
     if (check_for_node(node, "serialization")) {
-      serialization = get_node_value(node, "serialization", false, true);
+      // If the source is serialized then make sure we only load it from file once, otherwise there will
+      // be a significant I/O overhead.
+      pugi::xml_document doc;
+      doc.load_file(get_node_value(node, "serialization", false, true).c_str());
+      std::stringstream ss;
+      doc.print(ss);
+      serialization = ss.str();
     }
   } else {