diff --git a/hadoop-common-project/hadoop-common/CHANGES.txt b/hadoop-common-project/hadoop-common/CHANGES.txt
index f3b026feebc..c606f1cb998 100644
--- a/hadoop-common-project/hadoop-common/CHANGES.txt
+++ b/hadoop-common-project/hadoop-common/CHANGES.txt
@@ -382,6 +382,8 @@ Release 2.8.0 - UNRELEASED
 
     HADOOP-12696. Add tests for S3Filesystem Contract (Matt Paduano via raviprak)
 
+    HADOOP-12755. Fix typo in defaultFS warning message. (wang)
+
   OPTIMIZATIONS
 
     HADOOP-11785. Reduce the number of listStatus operation in distcp
diff --git a/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/fs/shell/FsCommand.java b/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/fs/shell/FsCommand.java
index 971950f755c..f274f673040 100644
--- a/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/fs/shell/FsCommand.java
+++ b/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/fs/shell/FsCommand.java
@@ -112,7 +112,7 @@ abstract public class FsCommand extends Command {
           defaultFs == null || defaultFs.equals(FS_DEFAULT_NAME_DEFAULT);
       if (missingDefaultFs) {
         err.printf(
-            "Warning: fs.defaultFs is not set when running \"%s\" command.%n",
+            "Warning: fs.defaultFS is not set when running \"%s\" command.%n",
             getCommandName());
       }
     }
diff --git a/hadoop-common-project/hadoop-common/src/test/java/org/apache/hadoop/fs/shell/TestLs.java b/hadoop-common-project/hadoop-common/src/test/java/org/apache/hadoop/fs/shell/TestLs.java
index cba44ee117c..0df1a6a8d3a 100644
--- a/hadoop-common-project/hadoop-common/src/test/java/org/apache/hadoop/fs/shell/TestLs.java
+++ b/hadoop-common-project/hadoop-common/src/test/java/org/apache/hadoop/fs/shell/TestLs.java
@@ -1062,7 +1062,7 @@ public class TestLs {
     ls.err = err;
     ls.run("file:///.");
     assertEquals(shouldDisplay, buf.toString().contains(
-        "Warning: fs.defaultFs is not set when running \"ls\" command."));
+        "Warning: fs.defaultFS is not set when running \"ls\" command."));
   }
 
   @Test