diff --git a/core/src/main/scala/org/apache/spark/ExecutorAllocationManager.scala b/core/src/main/scala/org/apache/spark/ExecutorAllocationManager.scala
index 5cb3160711a90..0b09f1fa2db2b 100644
--- a/core/src/main/scala/org/apache/spark/ExecutorAllocationManager.scala
+++ b/core/src/main/scala/org/apache/spark/ExecutorAllocationManager.scala
@@ -437,7 +437,7 @@ private[spark] class ExecutorAllocationManager(
           } else {
             logDebug(s"Lowering target number of executors to" +
               s" ${numExecutorsTargetPerResourceProfileId(rpId)} (previously " +
-              s"$targetNum.oldNumExecutorsTarget for resource profile id: ${rpId}) " +
+              s"${targetNum.oldNumExecutorsTarget} for resource profile id: ${rpId}) " +
               "because not all requested executors " +
               "are actually needed")
           }
diff --git a/core/src/test/scala/org/apache/spark/ExecutorAllocationManagerSuite.scala b/core/src/test/scala/org/apache/spark/ExecutorAllocationManagerSuite.scala
index 8fa33f4915ea4..9fac1199a80be 100644
--- a/core/src/test/scala/org/apache/spark/ExecutorAllocationManagerSuite.scala
+++ b/core/src/test/scala/org/apache/spark/ExecutorAllocationManagerSuite.scala
@@ -841,7 +841,10 @@ class ExecutorAllocationManagerSuite extends SparkFunSuite {
   }
 
   test ("interleaving add and remove") {
-    val manager = createManager(createConf(5, 12, 5))
+    // use ManualClock to disable ExecutorAllocationManager.schedule()
+    // in order to avoid unexpected update of target executors
+    val clock = new ManualClock()
+    val manager = createManager(createConf(5, 12, 5), clock)
     post(SparkListenerStageSubmitted(createStageInfo(0, 1000)))
 
     val updatesNeeded =