diff --git a/src/org/jruby/java/MiniJava.java b/src/org/jruby/java/MiniJava.java
index 15c43ab..bc7a13b 100644
--- a/src/org/jruby/java/MiniJava.java
+++ b/src/org/jruby/java/MiniJava.java
@@ -358,6 +358,9 @@ public class MiniJava implements Library {

         // construct the class, implementing all supertypes
         cw.visit(V1_5, ACC_PUBLIC | ACC_SUPER, name, null, p(Object.class), superTypeNames);
+
+        // Give it a filename
+        cw.visitSource(name, name);

         // fields needed for dispatch and such
         cw.visitField(ACC_STATIC | ACC_PRIVATE, "ruby", ci(Ruby.class), null, null).visitEnd();
@@ -424,10 +427,12 @@ public class MiniJava implements Library {
                 } else {
                     Label dispatch = new Label();
                     Label end = new Label();
+                    Label line;

                     // Try to look up field for simple name

                     // lock self
+                    line = new Label(); mv.visitLineNumber(1, line); mv.label(line);
                     mv.getstatic(name, "rubyClass", ci(RubyClass.class));
                     mv.monitorenter();

@@ -455,6 +460,7 @@ public class MiniJava implements Library {
                     mv.pop();
                     // exit monitor before making call
                     // FIXME: this not being in a finally is a little worrisome
+                    line = new Label(); mv.visitLineNumber(2, line); mv.label(line);
                     mv.getstatic(name, "rubyClass", ci(RubyClass.class));
                     mv.monitorexit();
                     mv.aload(0);
@@ -468,7 +474,8 @@ public class MiniJava implements Library {
                     mv.label(dispatch);
                     mv.dup();
                     mv.putstatic(name, simpleName, ci(DynamicMethod.class));
-
+
+                    line = new Label(); mv.visitLineNumber(3, line); mv.label(line);
                     mv.getstatic(name, "rubyClass", ci(RubyClass.class));
                     mv.monitorexit();

@@ -493,7 +500,7 @@ public class MiniJava implements Library {

                     mv.label(end);
                     coerceResultAndReturn(method, mv, returnType);
-                }
+                }
                 mv.end();
             }
         }