diff --git a/core/src/main/java/ch/dissem/bitmessage/BitmessageContext.java b/core/src/main/java/ch/dissem/bitmessage/BitmessageContext.java
index 2307958..aef6a67 100644
--- a/core/src/main/java/ch/dissem/bitmessage/BitmessageContext.java
+++ b/core/src/main/java/ch/dissem/bitmessage/BitmessageContext.java
@@ -69,7 +69,7 @@ public class BitmessageContext {
     private BitmessageContext(Builder builder) {
         ctx = new InternalContext(builder);
         labeler = builder.labeler;
-        ctx.getProofOfWorkService().doMissingProofOfWork();
+        ctx.getProofOfWorkService().doMissingProofOfWork(30_000); // TODO: this should be configurable
 
         networkListener = new DefaultMessageListener(ctx, labeler, builder.listener);
         sendPubkeyOnIdentityCreation = builder.sendPubkeyOnIdentityCreation;
diff --git a/core/src/main/java/ch/dissem/bitmessage/ProofOfWorkService.java b/core/src/main/java/ch/dissem/bitmessage/ProofOfWorkService.java
index d242b79..04016b5 100644
--- a/core/src/main/java/ch/dissem/bitmessage/ProofOfWorkService.java
+++ b/core/src/main/java/ch/dissem/bitmessage/ProofOfWorkService.java
@@ -30,7 +30,7 @@ public class ProofOfWorkService implements ProofOfWorkEngine.Callback, InternalC
     private ProofOfWorkRepository powRepo;
     private MessageRepository messageRepo;
 
-    public void doMissingProofOfWork() {
+    public void doMissingProofOfWork(long delayInMilliseconds) {
         final List<byte[]> items = powRepo.getItems();
         if (items.isEmpty()) return;
 
@@ -45,7 +45,7 @@ public class ProofOfWorkService implements ProofOfWorkEngine.Callback, InternalC
                             ProofOfWorkService.this);
                 }
             }
-        }, 30_000);
+        }, delayInMilliseconds);
     }
 
     public void doProofOfWork(ObjectMessage object) {
diff --git a/core/src/test/java/ch/dissem/bitmessage/ProofOfWorkServiceTest.java b/core/src/test/java/ch/dissem/bitmessage/ProofOfWorkServiceTest.java
index fa58cfe..c4529e3 100644
--- a/core/src/test/java/ch/dissem/bitmessage/ProofOfWorkServiceTest.java
+++ b/core/src/test/java/ch/dissem/bitmessage/ProofOfWorkServiceTest.java
@@ -77,9 +77,9 @@ public class ProofOfWorkServiceTest {
         when(proofOfWorkRepo.getItem(any(byte[].class))).thenReturn(new ProofOfWorkRepository.Item(null, 1001, 1002));
         doNothing().when(cryptography).doProofOfWork(any(ObjectMessage.class), anyLong(), anyLong(), any(ProofOfWorkEngine.Callback.class));
 
-        proofOfWorkService.doMissingProofOfWork();
+        proofOfWorkService.doMissingProofOfWork(10);
 
-        verify(cryptography).doProofOfWork((ObjectMessage) isNull(), eq(1001L), eq(1002L),
+        verify(cryptography, timeout(1000)).doProofOfWork((ObjectMessage) isNull(), eq(1001L), eq(1002L),
                 any(ProofOfWorkEngine.Callback.class));
     }