diff --git a/pom.xml b/pom.xml
index c6bc24dd9..b73d70f3a 100644
--- a/pom.xml
+++ b/pom.xml
@@ -49,10 +49,11 @@
   </contributors>
 
   <dependencies>
+    <!-- Plexus dependencies -->
     <dependency>
       <groupId>org.codehaus.plexus</groupId>
       <artifactId>plexus-container-default</artifactId>
-      <version>1.0-alpha-30</version>
+      <version>2.1.1</version>
       <scope>provided</scope>
     </dependency>
     <dependency>
@@ -65,21 +66,28 @@
       <artifactId>plexus-io</artifactId>
       <version>3.2.0</version>
     </dependency>
+    <!-- Apache Commons dependencies -->
+    <dependency>
+      <groupId>commons-io</groupId>
+      <artifactId>commons-io</artifactId>
+      <version>2.11.0</version>
+    </dependency>
     <dependency>
       <groupId>org.apache.commons</groupId>
       <artifactId>commons-compress</artifactId>
       <version>1.21</version>
     </dependency>
+    <!-- Other dependencies -->
     <dependency>
       <groupId>org.iq80.snappy</groupId>
       <artifactId>snappy</artifactId>
       <version>0.4</version>
     </dependency>
     <dependency>
-      <groupId>junit</groupId>
-      <artifactId>junit</artifactId>
-      <version>4.13.2</version>
-      <scope>test</scope>
+      <groupId>org.tukaani</groupId>
+      <artifactId>xz</artifactId>
+      <version>1.9</version>
+      <scope>runtime</scope>
     </dependency>
     <dependency>
       <groupId>com.google.code.findbugs</groupId>
@@ -87,15 +95,15 @@
       <version>3.0.2</version>
       <scope>provided</scope>
     </dependency>
+    <!-- Test dependencies -->
     <dependency>
-      <groupId>org.tukaani</groupId>
-      <artifactId>xz</artifactId>
-      <version>1.9</version>
-      <scope>runtime</scope>
+      <groupId>junit</groupId>
+      <artifactId>junit</artifactId>
+      <version>4.13.2</version>
+      <scope>test</scope>
     </dependency>
   </dependencies>
 
-
   <build>
     <plugins>
       <plugin>
diff --git a/src/main/java/org/codehaus/plexus/archiver/AbstractUnArchiver.java b/src/main/java/org/codehaus/plexus/archiver/AbstractUnArchiver.java
index f3f389edc..a4a094c6b 100644
--- a/src/main/java/org/codehaus/plexus/archiver/AbstractUnArchiver.java
+++ b/src/main/java/org/codehaus/plexus/archiver/AbstractUnArchiver.java
@@ -25,6 +25,7 @@
 import java.util.ArrayList;
 import java.util.Date;
 import java.util.List;
+import java.util.Locale;
 
 import org.codehaus.plexus.archiver.util.ArchiveEntryUtils;
 import org.codehaus.plexus.components.io.attributes.SymlinkUtils;
@@ -412,7 +413,7 @@ protected boolean shouldExtractEntry( File targetDirectory, File targetFileName,
         boolean fileOnDiskIsNewerThanEntry = targetFileName.lastModified() >= entryDate.getTime();
         boolean differentCasing = !entryName.equals( relativeCanonicalDestPath );
 
-        String casingMessage = String.format( "Archive entry '%s' and existing file '%s' names differ only by case."
+        String casingMessage = String.format( Locale.ENGLISH, "Archive entry '%s' and existing file '%s' names differ only by case."
                 + " This may lead to an unexpected outcome on case-insensitive filesystems.", entryName, canonicalDestPath );
 
         // (1)
diff --git a/src/main/java/org/codehaus/plexus/archiver/jar/JarToolModularJarArchiver.java b/src/main/java/org/codehaus/plexus/archiver/jar/JarToolModularJarArchiver.java
index ad09199fc..f58281192 100644
--- a/src/main/java/org/codehaus/plexus/archiver/jar/JarToolModularJarArchiver.java
+++ b/src/main/java/org/codehaus/plexus/archiver/jar/JarToolModularJarArchiver.java
@@ -36,7 +36,7 @@
 import java.util.zip.ZipOutputStream;
 
 import org.apache.commons.compress.parallel.InputStreamSupplier;
-import org.apache.commons.io.output.NullOutputStream;
+import org.apache.commons.io.output.NullPrintStream;
 import org.codehaus.plexus.archiver.ArchiverException;
 import org.codehaus.plexus.archiver.zip.ConcurrentJarCreator;
 import org.codehaus.plexus.util.IOUtil;
@@ -294,7 +294,7 @@ private boolean isJarDateOptionSupported( Method runMethod )
             // Test the output code validating the --date option.
             String[] args = { "--date", "2099-12-31T23:59:59Z", "--version" };
 
-            PrintStream nullPrintStream = new PrintStream( NullOutputStream.NULL_OUTPUT_STREAM );
+            PrintStream nullPrintStream = NullPrintStream.NULL_PRINT_STREAM;
             Integer result = (Integer) runMethod.invoke( jarTool, nullPrintStream, nullPrintStream, args );
 
             return result != null && result.intValue() == 0;
diff --git a/src/main/java/org/codehaus/plexus/archiver/jar/Manifest.java b/src/main/java/org/codehaus/plexus/archiver/jar/Manifest.java
index df1fb83c4..587bdebb1 100644
--- a/src/main/java/org/codehaus/plexus/archiver/jar/Manifest.java
+++ b/src/main/java/org/codehaus/plexus/archiver/jar/Manifest.java
@@ -510,7 +510,7 @@ public Iterator<String> iterator()
          */
         public Attribute getAttribute( String attributeName )
         {
-            return attributes.get( attributeName.toLowerCase() );
+            return attributes.get( attributeName.toLowerCase( Locale.ENGLISH ) );
         }
 
         /**
diff --git a/src/test/java/org/codehaus/plexus/archiver/DuplicateFilesTest.java b/src/test/java/org/codehaus/plexus/archiver/DuplicateFilesTest.java
index 2728c24c1..afab59f3d 100644
--- a/src/test/java/org/codehaus/plexus/archiver/DuplicateFilesTest.java
+++ b/src/test/java/org/codehaus/plexus/archiver/DuplicateFilesTest.java
@@ -3,14 +3,13 @@
 import java.io.BufferedInputStream;
 import java.io.BufferedReader;
 import java.io.File;
-import java.io.FileInputStream;
-import java.io.FileReader;
 import java.nio.charset.StandardCharsets;
 import java.nio.file.Files;
 import java.util.Enumeration;
 
 import org.apache.commons.compress.archivers.tar.TarArchiveInputStream;
 import org.apache.commons.compress.archivers.zip.ZipArchiveEntry;
+import org.codehaus.plexus.DefaultPlexusContainer;
 import org.codehaus.plexus.PlexusTestCase;
 import org.codehaus.plexus.archiver.tar.TarArchiver;
 import org.codehaus.plexus.archiver.tar.TarLongFileMode;
@@ -34,7 +33,8 @@ public void setUp()
         throws Exception
     {
         super.setUp();
-        getContainer().getLoggerManager().setThreshold( Logger.LEVEL_DEBUG );
+        DefaultPlexusContainer container = (DefaultPlexusContainer) getContainer();
+        container.getLoggerManager().setThreshold( Logger.LEVEL_DEBUG );
     }
 
     public void testZipArchiver()