diff --git a/src/test/groovy/io/emeraldpay/dshackle/rpc/TrackEthereumAddressSpec.groovy b/src/test/groovy/io/emeraldpay/dshackle/rpc/TrackEthereumAddressSpec.groovy
index 5343aa12..e68f7843 100644
--- a/src/test/groovy/io/emeraldpay/dshackle/rpc/TrackEthereumAddressSpec.groovy
+++ b/src/test/groovy/io/emeraldpay/dshackle/rpc/TrackEthereumAddressSpec.groovy
@@ -118,6 +118,7 @@ class TrackEthereumAddressSpec extends Specification {
                 .expectNext(exp1).as("First block")
                 .then {
                     upstreamMock.nextBlock(BlockContainer.from(block2, TestingCommons.objectMapper()))
+                    Thread.sleep(50)
                 }
                 .expectNext(exp2).as("Second block")
                 .thenCancel()
diff --git a/src/test/groovy/io/emeraldpay/dshackle/upstream/ethereum/EthereumReaderSpec.groovy b/src/test/groovy/io/emeraldpay/dshackle/upstream/ethereum/EthereumReaderSpec.groovy
index 06349b14..602af14e 100644
--- a/src/test/groovy/io/emeraldpay/dshackle/upstream/ethereum/EthereumReaderSpec.groovy
+++ b/src/test/groovy/io/emeraldpay/dshackle/upstream/ethereum/EthereumReaderSpec.groovy
@@ -235,6 +235,7 @@ class EthereumReaderSpec extends Specification {
             it.totalDifficulty = BigInteger.TWO
         }
         upstream.nextBlock(BlockContainer.from(block2, TestingCommons.objectMapper()))
+        Thread.sleep(50)
         act = reader.balance().read(Address.from("0x70b91ff87a902b53dc6e2f6bda8bb9b330ccd30c")).block()
 
         then: