diff --git a/src/main/java/org/torproject/metrics/onionoo/docs/DocumentStore.java b/src/main/java/org/torproject/metrics/onionoo/docs/DocumentStore.java
index e7fa7c9..ba242e8 100644
--- a/src/main/java/org/torproject/metrics/onionoo/docs/DocumentStore.java
+++ b/src/main/java/org/torproject/metrics/onionoo/docs/DocumentStore.java
@@ -561,7 +561,7 @@ private <T extends Document> T retrieveParsedDocumentFile(
       Class<T> documentType, String documentString) {
     T result = null;
     try {
-      if (!documentString.isEmpty() && !documentString.equals("{}")) {
+      if (documentString != null && !documentString.isEmpty() && !documentString.equals("{}")) {
         result = objectMapper.readValue(documentString, documentType);
       }
     } catch (Throwable e) {