diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/blockmanagement/DatanodeManager.java b/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/blockmanagement/DatanodeManager.java
index 6939e65ba8..8e5a24ba60 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/blockmanagement/DatanodeManager.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/blockmanagement/DatanodeManager.java
@@ -1658,7 +1658,7 @@ private BlockRecoveryCommand getBlockRecoveryCommand(String blockPoolId,
       BlockUnderConstructionFeature uc = b.getUnderConstructionFeature();
       if(uc == null) {
         throw new IOException("Recovery block " + b +
-            "where it is not under construction.");
+            " where it is not under construction.");
       }
       final DatanodeStorageInfo[] storages = uc.getExpectedStorageLocations();
       // Skip stale nodes during recovery