diff --git a/Makefile b/Makefile
index b5787f9..692ff49 100644
--- a/Makefile
+++ b/Makefile
@@ -1,4 +1,8 @@
 repl:
 	gradle compileJava && rlwrap java -cp build/classes/java/main/ serene.simple.Main
+
+run:
+	gradle compileJava && java -cp build/classes/java/main/ serene.simple.Main ${PWD}/test.srns
+
 docs:
 	npx docco src/**/*.java
diff --git a/src/main/java/serene/simple/AScope.java b/src/main/java/serene/simple/AScope.java
index a9392eb..1f23916 100644
--- a/src/main/java/serene/simple/AScope.java
+++ b/src/main/java/serene/simple/AScope.java
@@ -1,3 +1,4 @@
+
 /**
  * Serene (simple) - A PoC lisp to collect data on Serenes concepts
  * Copyright (C) 2019-2020 Sameer Rahmani <lxsameer@gnu.org>
@@ -47,7 +48,7 @@ public abstract class AScope implements IScope {
   public Object lookupSymbol(String symbolName) {
     Object value = this.getLocalSymbol(symbolName);
 
-    if (value != null) {
+    if (!(value instanceof Null)) {
       return value;
     }
     else if (this.parent() != null) {
@@ -68,6 +69,8 @@ public abstract class AScope implements IScope {
       return this.symbols().get(symbolName);
     }
 
-    return null;
+    return new Null();
   }
+
+  private class Null {}
 }
diff --git a/src/main/java/serene/simple/CondSpecialForm.java b/src/main/java/serene/simple/CondSpecialForm.java
index 38bf319..ad77411 100644
--- a/src/main/java/serene/simple/CondSpecialForm.java
+++ b/src/main/java/serene/simple/CondSpecialForm.java
@@ -30,7 +30,7 @@ public class CondSpecialForm extends SpecialForm {
       throw new SereneException("Let bindings should be a list of pairs.");
     }
 
-    this.conditions = (ListNode<Node>) listNode.rest().first();
+    this.conditions = (ListNode<Node>) listNode.rest();
   }
 
   @Override
diff --git a/src/main/java/serene/simple/FnSpecialForm.java b/src/main/java/serene/simple/FnSpecialForm.java
index 7cc3a17..8a681e3 100644
--- a/src/main/java/serene/simple/FnSpecialForm.java
+++ b/src/main/java/serene/simple/FnSpecialForm.java
@@ -38,9 +38,11 @@ public class FnSpecialForm extends SpecialForm {
 
         Scope scope = new Scope(parentScope);
         if (args.length != formalParams.length) {
-          throw new RuntimeException(String.format("Wrong number of arguments. Expected: %s, Got: %s.",
-                                                   formalParams.length,
-                                                   args.length));
+          throw new RuntimeException(
+            String.format("Wrong number of arguments. Expected: %s, Got: %s. ARGS: %s",
+                          formalParams.length,
+                          args.length,
+                          args.toString()));
         }
         // Map parameter values to formal parameter names
         int i = 0;
diff --git a/src/main/java/serene/simple/Main.java b/src/main/java/serene/simple/Main.java
index 4aa3d8c..814256b 100644
--- a/src/main/java/serene/simple/Main.java
+++ b/src/main/java/serene/simple/Main.java
@@ -109,8 +109,8 @@ public class Main {
 
   private static void runSerene(String filePath) throws IOException {
     IScope rootScope = new RootScope();
-
-    ListNode<Node> nodes = Reader.read(new FileInputStream(filePath));
+    FileInputStream input = new FileInputStream(filePath);
+    ListNode<Node> nodes = Reader.read(input);
 
     for (Node n : nodes) {
       n.eval(rootScope);
diff --git a/src/main/java/serene/simple/Reader.java b/src/main/java/serene/simple/Reader.java
index d1bdca4..bbe8979 100644
--- a/src/main/java/serene/simple/Reader.java
+++ b/src/main/java/serene/simple/Reader.java
@@ -67,7 +67,15 @@ public class Reader {
     char c = (char) inputStream.read();
     while ((byte) c != -1) {
       if (c == ';') {
-        break;
+        while(true) {
+          char commentChar = (char) inputStream.read();
+
+          if (commentChar == '\n') {
+            break;
+          }
+        }
+        c = (char) inputStream.read();
+        continue;
       }
 
       inputStream.unread(c);
diff --git a/src/main/java/serene/simple/RootScope.java b/src/main/java/serene/simple/RootScope.java
index a930354..cd48352 100644
--- a/src/main/java/serene/simple/RootScope.java
+++ b/src/main/java/serene/simple/RootScope.java
@@ -44,11 +44,14 @@ public class RootScope extends AScope {
       put("or", new OrFn());
       put("not", new NotFn());
       put("conj", new ConjFn());
+      put("cons", new ConjFn());
+      // put("size", new SizeFn());
+      // put("reverse", new SizeFn());
       put("list", new ListFn());
       put("first", new FirstFn());
       put("rest", new RestFn());
-      // put("cond", new CondFn());
-      //put("reduce", new ReduceFn());
+      // put("doc", new DocFn());
+      // put("reduce", new ReduceFn());
       put("System", System.class);
       put("Boolean", Boolean.class);
       put("String", String.class);
diff --git a/src/main/java/serene/simple/builtin/ConjFn.java b/src/main/java/serene/simple/builtin/ConjFn.java
index 4742077..bc19c24 100644
--- a/src/main/java/serene/simple/builtin/ConjFn.java
+++ b/src/main/java/serene/simple/builtin/ConjFn.java
@@ -45,7 +45,7 @@ public class ConjFn extends AFn {
     ListNode<Object> list = (ListNode<Object>) args.get(0);
 
     for (Object x : args.subList(1, args.size())) {
-      list = new ListNode<Object>(x, list);
+      list = list.cons(x);
     }
 
     return list;
diff --git a/src/main/java/serene/simple/builtin/PrintlnFn.java b/src/main/java/serene/simple/builtin/PrintlnFn.java
index a1cdcf8..a6239ee 100644
--- a/src/main/java/serene/simple/builtin/PrintlnFn.java
+++ b/src/main/java/serene/simple/builtin/PrintlnFn.java
@@ -19,6 +19,8 @@
  */
 package serene.simple.builtin;
 
+import java.util.List;
+
 import serene.simple.IScope;
 
 
@@ -28,12 +30,17 @@ public class PrintlnFn extends AFn {
   };
 
   public Object eval(IScope scope) {
-    String output = "";
+    List<Object> args = this.arguments();
 
-    for(Object x: this.arguments()) {
-      output = String.format(
-        "%s %s", output,
-        (String) x.toString());
+    if (args.size() == 0) {
+      System.out.println("");
+      return null;
+    }
+
+    String output = args.get(0).toString();
+
+    for(Object x: args.subList(1, args.size())) {
+      output = output + " " + x.toString();
     }
 
     System.out.println(output);