diff --git a/code/features-convert/anchor-keywords/src/main/java/nu/marginalia/atags/source/AnchorTagsImpl.java b/code/features-convert/anchor-keywords/src/main/java/nu/marginalia/atags/source/AnchorTagsImpl.java
index 9004b2ac..bd537c6e 100644
--- a/code/features-convert/anchor-keywords/src/main/java/nu/marginalia/atags/source/AnchorTagsImpl.java
+++ b/code/features-convert/anchor-keywords/src/main/java/nu/marginalia/atags/source/AnchorTagsImpl.java
@@ -60,7 +60,7 @@ public class AnchorTagsImpl implements AnchorTagsSource {
     }
 
     @Override
-    public DomainLinks getAnchorTags(EdgeDomain domain) {
+    public synchronized DomainLinks getAnchorTags(EdgeDomain domain) {
         List<LinkWithText> links = new ArrayList<>();
 
         try (var ps = duckdbConnection.prepareStatement("""