diff --git a/core/src/net/sf/openrocket/util/StringUtil.java b/core/src/net/sf/openrocket/util/StringUtil.java
index 407e0bad6..e5c3bb2ee 100644
--- a/core/src/net/sf/openrocket/util/StringUtil.java
+++ b/core/src/net/sf/openrocket/util/StringUtil.java
@@ -8,8 +8,10 @@ public class StringUtil {
 	 * This is implemented without using String.isEmpty() because that method
 	 * is not available in Froyo.
 	 * 
-	 * @param s
-	 * @return
+	 * @param s string to check
+	 * @return true iff s is null or trims to
+	 * an empty string, where trim is defined
+	 * by {@link java.lang.String#trim}
 	 */
 	public static boolean isEmpty( String s ) {
 		if ( s == null ) {
diff --git a/core/test/net/sf/openrocket/util/StringUtilTest.java b/core/test/net/sf/openrocket/util/StringUtilTest.java
new file mode 100644
index 000000000..2d89772e5
--- /dev/null
+++ b/core/test/net/sf/openrocket/util/StringUtilTest.java
@@ -0,0 +1,25 @@
+package net.sf.openrocket.util;
+
+import org.junit.Test;
+
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertTrue;
+
+/**
+ * A class that tests
+ * {@link net.sf.openrocket.util.StringUtil}.
+ */
+public class StringUtilTest {
+    @Test
+    public void testStrings() {
+        assertTrue(StringUtil.isEmpty(""));
+        assertTrue(StringUtil.isEmpty(new StringBuilder().toString())); // ""
+        assertTrue(StringUtil.isEmpty(" "));
+        assertTrue(StringUtil.isEmpty("  "));
+        assertTrue(StringUtil.isEmpty("       "));
+        assertTrue(StringUtil.isEmpty(null));
+
+        assertFalse(StringUtil.isEmpty("A"));
+        assertFalse(StringUtil.isEmpty("         .        "));
+    }
+}