diff --git a/jadx-core/src/main/java/jadx/core/clsp/ClspGraph.java b/jadx-core/src/main/java/jadx/core/clsp/ClspGraph.java
index 2f78059c8..674250fde 100644
--- a/jadx-core/src/main/java/jadx/core/clsp/ClspGraph.java
+++ b/jadx-core/src/main/java/jadx/core/clsp/ClspGraph.java
@@ -23,7 +23,7 @@ import org.slf4j.LoggerFactory;
 public class ClspGraph {
 	private static final Logger LOG = LoggerFactory.getLogger(ClspGraph.class);
 
-	private final Map<String, Set<String>> ancestorCache = new WeakHashMap<String, Set<String>>();
+	private final Map<String, Set<String>> ancestorCache = Collections.synchronizedMap(new WeakHashMap<String, Set<String>>());
 	private Map<String, NClass> nameMap;
 
 	private final Set<String> missingClasses = new HashSet<String>();