diff --git a/maven-plugin-tools-api/src/test/java/org/apache/maven/tools/plugin/generator/PluginHelpGeneratorTest.java b/maven-plugin-tools-api/src/test/java/org/apache/maven/tools/plugin/generator/PluginHelpGeneratorTest.java
index 41e8724..8c0eca7 100644
--- a/maven-plugin-tools-api/src/test/java/org/apache/maven/tools/plugin/generator/PluginHelpGeneratorTest.java
+++ b/maven-plugin-tools-api/src/test/java/org/apache/maven/tools/plugin/generator/PluginHelpGeneratorTest.java
@@ -29,7 +29,9 @@ public class PluginHelpGeneratorTest
     public void testToText()
         throws Exception
     {
-        String javadoc = "";
+        String javadoc = null;
+        assertEquals( "", PluginHelpGenerator.toText( javadoc ) );
+        javadoc = "";
         assertEquals( "", PluginHelpGenerator.toText( javadoc ) );
 
         // line breaks
diff --git a/maven-plugin-tools-api/src/test/java/org/apache/maven/tools/plugin/util/PluginUtilsTest.java b/maven-plugin-tools-api/src/test/java/org/apache/maven/tools/plugin/util/PluginUtilsTest.java
index 5ab8e24..ab6285a 100644
--- a/maven-plugin-tools-api/src/test/java/org/apache/maven/tools/plugin/util/PluginUtilsTest.java
+++ b/maven-plugin-tools-api/src/test/java/org/apache/maven/tools/plugin/util/PluginUtilsTest.java
@@ -121,7 +121,9 @@ public class PluginUtilsTest
 
     public void testMakeHtmlValid()
     {
-        String javadoc = "";
+        String javadoc = null;
+        assertEquals( "", PluginUtils.makeHtmlValid( javadoc ) );
+        javadoc = "";
         assertEquals( "", PluginUtils.makeHtmlValid( javadoc ) );
 
         // true HTML