diff --git a/hadoop-maven-plugins/src/main/java/org/apache/hadoop/maven/plugin/cmakebuilder/CompileMojo.java b/hadoop-maven-plugins/src/main/java/org/apache/hadoop/maven/plugin/cmakebuilder/CompileMojo.java
index afb11cbdca9..0196352816a 100644
--- a/hadoop-maven-plugins/src/main/java/org/apache/hadoop/maven/plugin/cmakebuilder/CompileMojo.java
+++ b/hadoop-maven-plugins/src/main/java/org/apache/hadoop/maven/plugin/cmakebuilder/CompileMojo.java
@@ -14,6 +14,7 @@
 
 package org.apache.hadoop.maven.plugin.cmakebuilder;
 
+import java.util.Locale;
 import org.apache.hadoop.maven.plugin.util.Exec.OutputBufferThread;
 import org.apache.hadoop.maven.plugin.util.Exec;
 import org.apache.maven.plugin.AbstractMojo;
@@ -83,7 +84,8 @@ public class CompileMojo extends AbstractMojo {
 
   // TODO: support Windows
   private static void validatePlatform() throws MojoExecutionException {
-    if (System.getProperty("os.name").toLowerCase().startsWith("windows")) {
+    if (System.getProperty("os.name").toLowerCase(Locale.ENGLISH)
+        .startsWith("windows")) {
       throw new MojoExecutionException("CMakeBuilder does not yet support " +
           "the Windows platform.");
     }
diff --git a/hadoop-maven-plugins/src/main/java/org/apache/hadoop/maven/plugin/cmakebuilder/TestMojo.java b/hadoop-maven-plugins/src/main/java/org/apache/hadoop/maven/plugin/cmakebuilder/TestMojo.java
index e676efd1664..95b6264ba60 100644
--- a/hadoop-maven-plugins/src/main/java/org/apache/hadoop/maven/plugin/cmakebuilder/TestMojo.java
+++ b/hadoop-maven-plugins/src/main/java/org/apache/hadoop/maven/plugin/cmakebuilder/TestMojo.java
@@ -14,6 +14,7 @@
 
 package org.apache.hadoop.maven.plugin.cmakebuilder;
 
+import java.util.Locale;
 import org.apache.hadoop.maven.plugin.util.Exec;
 import org.apache.maven.execution.MavenSession;
 import org.apache.maven.plugin.AbstractMojo;
@@ -117,7 +118,8 @@ public class TestMojo extends AbstractMojo {
 
   // TODO: support Windows
   private static void validatePlatform() throws MojoExecutionException {
-    if (System.getProperty("os.name").toLowerCase().startsWith("windows")) {
+    if (System.getProperty("os.name").toLowerCase(Locale.ENGLISH)
+        .startsWith("windows")) {
       throw new MojoExecutionException("CMakeBuilder does not yet support " +
           "the Windows platform.");
     }
diff --git a/hadoop-maven-plugins/src/main/java/org/apache/hadoop/maven/plugin/protoc/ProtocMojo.java b/hadoop-maven-plugins/src/main/java/org/apache/hadoop/maven/plugin/protoc/ProtocMojo.java
index 0dcac0e8e45..df479fd4872 100644
--- a/hadoop-maven-plugins/src/main/java/org/apache/hadoop/maven/plugin/protoc/ProtocMojo.java
+++ b/hadoop-maven-plugins/src/main/java/org/apache/hadoop/maven/plugin/protoc/ProtocMojo.java
@@ -105,6 +105,10 @@ public class ProtocMojo extends AbstractMojo {
     private boolean hasDirectoryChanged(File directory) throws IOException {
       File[] listing = directory.listFiles();
       boolean changed = false;
+      if (listing == null) {
+        // not changed.
+        return false;
+      }
       // Do not exit early, since we need to compute and save checksums
       // for each file within the directory.
       for (File f : listing) {
diff --git a/hadoop-maven-plugins/src/main/java/org/apache/hadoop/maven/plugin/util/Exec.java b/hadoop-maven-plugins/src/main/java/org/apache/hadoop/maven/plugin/util/Exec.java
index decfca406f3..528163103da 100644
--- a/hadoop-maven-plugins/src/main/java/org/apache/hadoop/maven/plugin/util/Exec.java
+++ b/hadoop-maven-plugins/src/main/java/org/apache/hadoop/maven/plugin/util/Exec.java
@@ -84,8 +84,10 @@ public class Exec {
       if (errors != null) {
         errors.addAll(stdErr.getOutput());
       }
-    } catch (Exception ex) {
-      mojo.getLog().warn(command + " failed: " + ex.toString());
+    } catch (IOException ioe) {
+      mojo.getLog().warn(command + " failed: " + ioe.toString());
+    } catch (InterruptedException ie) {
+      mojo.getLog().warn(command + " failed: " + ie.toString());
     }
     return retCode;
   }
diff --git a/hadoop-maven-plugins/src/main/java/org/apache/hadoop/maven/plugin/versioninfo/VersionInfoMojo.java b/hadoop-maven-plugins/src/main/java/org/apache/hadoop/maven/plugin/versioninfo/VersionInfoMojo.java
index b6a45ecfb8f..cd2651bb8ba 100644
--- a/hadoop-maven-plugins/src/main/java/org/apache/hadoop/maven/plugin/versioninfo/VersionInfoMojo.java
+++ b/hadoop-maven-plugins/src/main/java/org/apache/hadoop/maven/plugin/versioninfo/VersionInfoMojo.java
@@ -13,6 +13,7 @@
  */
 package org.apache.hadoop.maven.plugin.versioninfo;
 
+import java.io.Serializable;
 import java.util.Locale;
 import org.apache.hadoop.maven.plugin.util.Exec;
 import org.apache.hadoop.maven.plugin.util.FileSetUtils;
@@ -149,27 +150,23 @@ public class VersionInfoMojo extends AbstractMojo {
    */
   private String[] getSvnUriInfo(String str) {
     String[] res = new String[]{"Unknown", "Unknown"};
-    try {
-      String path = str;
-      int index = path.indexOf("trunk");
+    String path = str;
+    int index = path.indexOf("trunk");
+    if (index > -1) {
+      res[0] = path.substring(0, index - 1);
+      res[1] = "trunk";
+    } else {
+      index = path.indexOf("branches");
       if (index > -1) {
         res[0] = path.substring(0, index - 1);
-        res[1] = "trunk";
-      } else {
-        index = path.indexOf("branches");
+        int branchIndex = index + "branches".length() + 1;
+        index = path.indexOf("/", branchIndex);
         if (index > -1) {
-          res[0] = path.substring(0, index - 1);
-          int branchIndex = index + "branches".length() + 1;
-          index = path.indexOf("/", branchIndex);
-          if (index > -1) {
-            res[1] = path.substring(branchIndex, index);
-          } else {
-            res[1] = path.substring(branchIndex);
-          }
+          res[1] = path.substring(branchIndex, index);
+        } else {
+          res[1] = path.substring(branchIndex);
         }
       }
-    } catch (Exception ex) {
-      getLog().warn("Could not determine URI & branch from SVN URI: " + str);
     }
     return res;
   }
@@ -311,6 +308,20 @@ public class VersionInfoMojo extends AbstractMojo {
     return sb.toString();
   }
 
+  static class MD5Comparator implements Comparator<File>, Serializable {
+    private static final long serialVersionUID = 1L;
+
+    @Override
+    public int compare(File lhs, File rhs) {
+      return normalizePath(lhs).compareTo(normalizePath(rhs));
+    }
+
+    private String normalizePath(File file) {
+      return file.getPath().toUpperCase(Locale.ENGLISH)
+          .replaceAll("\\\\", "/");
+    }
+  }
+
   /**
    * Computes and returns an MD5 checksum of the contents of all files in the
    * input Maven FileSet.
@@ -323,17 +334,7 @@ public class VersionInfoMojo extends AbstractMojo {
     // File order of MD5 calculation is significant.  Sorting is done on
     // unix-format names, case-folded, in order to get a platform-independent
     // sort and calculate the same MD5 on all platforms.
-    Collections.sort(files, new Comparator<File>() {
-      @Override
-      public int compare(File lhs, File rhs) {
-        return normalizePath(lhs).compareTo(normalizePath(rhs));
-      }
-
-      private String normalizePath(File file) {
-        return file.getPath().toUpperCase(Locale.ENGLISH)
-            .replaceAll("\\\\", "/");
-      }
-    });
+    Collections.sort(files, new MD5Comparator());
     byte[] md5 = computeMD5(files);
     String md5str = byteArrayToString(md5);
     getLog().info("Computed MD5: " + md5str);