diff --git a/core/src/main/java/org/apache/spark/shuffle/unsafe/UnsafeShuffleExternalSorter.java b/core/src/main/java/org/apache/spark/shuffle/unsafe/UnsafeShuffleExternalSorter.java
index 3cf99307c47cc..772ed688359dc 100644
--- a/core/src/main/java/org/apache/spark/shuffle/unsafe/UnsafeShuffleExternalSorter.java
+++ b/core/src/main/java/org/apache/spark/shuffle/unsafe/UnsafeShuffleExternalSorter.java
@@ -337,7 +337,7 @@ private void allocateSpaceForRecord(int requiredSpace) throws IOException {
             final long memoryAcquiredAfterSpilling = shuffleMemoryManager.tryToAcquire(PAGE_SIZE);
             if (memoryAcquiredAfterSpilling != PAGE_SIZE) {
               shuffleMemoryManager.release(memoryAcquiredAfterSpilling);
-              throw new IOException("Can't allocate memory!");
+              throw new IOException("Unable to acquire " + PAGE_SIZE + " bytes of memory");
             }
           }
         }
diff --git a/core/src/test/scala/org/apache/spark/shuffle/unsafe/UnsafeShuffleSuite.scala b/core/src/test/scala/org/apache/spark/shuffle/unsafe/UnsafeShuffleSuite.scala
index 8ff3abefea897..f7eefa2a3f40c 100644
--- a/core/src/test/scala/org/apache/spark/shuffle/unsafe/UnsafeShuffleSuite.scala
+++ b/core/src/test/scala/org/apache/spark/shuffle/unsafe/UnsafeShuffleSuite.scala
@@ -26,5 +26,8 @@ class UnsafeShuffleSuite extends ShuffleSuite with BeforeAndAfterAll {
 
   override def beforeAll() {
     conf.set("spark.shuffle.manager", "unsafe")
+    // UnsafeShuffleManager requires at least 128 MB of memory per task in order to be able to sort
+    // shuffle records.
+    conf.set("spark.shuffle.memoryFraction", "0.5")
   }
 }