diff --git a/src/main/org/apache/tools/ant/taskdefs/ExecuteJava.java b/src/main/org/apache/tools/ant/taskdefs/ExecuteJava.java
index 0bf852c20..d5e9b9fb6 100644
--- a/src/main/org/apache/tools/ant/taskdefs/ExecuteJava.java
+++ b/src/main/org/apache/tools/ant/taskdefs/ExecuteJava.java
@@ -179,6 +179,8 @@ public class ExecuteJava implements Runnable, TimeoutObserver {
             throw new BuildException("Could not find " + classname + "."
                                      + " Make sure you have it in your"
                                      + " classpath");
+        } catch (BuildException e) {
+            throw e;
         } catch (SecurityException e) {
             throw e;
         } catch (ThreadDeath e) {
diff --git a/src/main/org/apache/tools/ant/types/CommandlineJava.java b/src/main/org/apache/tools/ant/types/CommandlineJava.java
index fa69fc27d..8d1524161 100644
--- a/src/main/org/apache/tools/ant/types/CommandlineJava.java
+++ b/src/main/org/apache/tools/ant/types/CommandlineJava.java
@@ -141,6 +141,7 @@ public class CommandlineJava implements Cloneable {
                 p.putAll(mergePropertySets());
                 for (Enumeration e = variables.elements(); e.hasMoreElements();) {
                     Environment.Variable v = (Environment.Variable) e.nextElement();
+                    v.validate();
                     p.put(v.getKey(), v.getValue());
                 }
                 System.setProperties(p);
diff --git a/src/main/org/apache/tools/ant/types/Environment.java b/src/main/org/apache/tools/ant/types/Environment.java
index ea1999aac..494511fbd 100644
--- a/src/main/org/apache/tools/ant/types/Environment.java
+++ b/src/main/org/apache/tools/ant/types/Environment.java
@@ -109,13 +109,21 @@ public class Environment {
          * @throws BuildException if key or value are unassigned
          */
         public String getContent() throws BuildException {
+            validate();
+            StringBuffer sb = new StringBuffer(key.trim());
+            sb.append("=").append(value.trim());
+            return sb.toString();
+        }
+
+        /**
+         * checks whether all required attributes have been specified.
+         * @throws BuildException if key or value are unassigned
+         */
+        public void validate() {
             if (key == null || value == null) {
                 throw new BuildException("key and value must be specified "
                     + "for environment variables.");
             }
-            StringBuffer sb = new StringBuffer(key.trim());
-            sb.append("=").append(value.trim());
-            return sb.toString();
         }
     }