diff --git a/src/se/vidstige/jadb/Stream.java b/src/se/vidstige/jadb/Stream.java
index 5a1a31b..866a5fe 100644
--- a/src/se/vidstige/jadb/Stream.java
+++ b/src/se/vidstige/jadb/Stream.java
@@ -7,6 +7,10 @@ import java.io.OutputStream;
 import java.nio.charset.Charset;
 
 public class Stream {
+    private Stream() {
+        throw new IllegalStateException("Utility class");
+    }
+
     public static void copy(InputStream in, OutputStream out) throws IOException {
         byte[] buffer = new byte[1024 * 10];
         int len;
diff --git a/src/se/vidstige/jadb/managers/Bash.java b/src/se/vidstige/jadb/managers/Bash.java
index 6770a8d..34fddbb 100644
--- a/src/se/vidstige/jadb/managers/Bash.java
+++ b/src/se/vidstige/jadb/managers/Bash.java
@@ -1,6 +1,10 @@
 package se.vidstige.jadb.managers;
 
 public class Bash {
+    private Bash() {
+        throw new IllegalStateException("Utility class");
+    }
+
     public static String quote(String s) {
         // Check that s contains no whitespace
         if (s.matches("\\S+")) {