diff --git a/ext.lisp b/ext.lisp
index ea76e91..2ec0469 100644
--- a/ext.lisp
+++ b/ext.lisp
@@ -6,6 +6,10 @@
 ;; Quick shorthand 
 (defun dir () (directory))
 
+;; File manipulation
 (defun file-read (filename) (with-sd-card (str filename) (read str)))
 (defun file-append (filename data) (with-sd-card (str filename 2) (print data str)))
 (defun file-write (filename data) (with-sd-card (str filename 2) (print data str)))
+
+;; Maths
+(defun sq (x) (* x x))
diff --git a/extensions.ino b/extensions.ino
index 0c8aa00..3629162 100644
--- a/extensions.ino
+++ b/extensions.ino
@@ -12,7 +12,7 @@ object *fn_savescreen (object *args, object *env) {
   (void) env;
   #if defined(sdcardsupport)
   object *arg = checkstring(first(args));
-  sd_begin();
+  SDBegin();
   File file;
   char buffer[BUFFERSIZE];
   file = SD.open(MakeFilename(arg, buffer), FILE_WRITE);
@@ -88,7 +88,7 @@ const char stringsavescreen[] PROGMEM = "save-screen";
 const char doc_sym_def[] PROGMEM = "(symbol-def symbol [str])\n"
 "Prints the definition of a symbol (variable or function) defined in ulisp using the pretty printer."
 "If str is specified it prints to the specified stream. It returns no value.";
-
+//
 const char docsavescreen[] PROGMEM = "(save-screen filename)\n"
 "Saves an image of the text screen as a BMP file on the SD card.";
 
@@ -109,4 +109,4 @@ const tbl_entry_t *table (int n) {
 
 unsigned int tablesize (int n) {
   return tablesizes[n];
-}
\ No newline at end of file
+}
diff --git a/tdeck-ulisp.ino b/tdeck-ulisp.ino
index 1922baf..3312cda 100644
--- a/tdeck-ulisp.ino
+++ b/tdeck-ulisp.ino
@@ -6,7 +6,12 @@
 
 
 const char LispLibrary[] PROGMEM = 
-"(defun load-package (filename) (with-sd-card (str filename) (loop (let (ln (eval (read str))) (unless ln (return nothing))))))"
+"(defun load-package (filename)"
+"  (with-sd-card (str filename)"
+"    (loop"
+"      (let ((ln (eval (read str))))"
+"        (unless ln (return nothing))))))"
+
 "(defun save-package (filename list) (with-sd-card (str filename 2) (dolist (f list) (symbol-def f str))))"
 "(defun add-to-package (filename list) (with-sd-card (str filename 1) (dolist (f list) (symbol-def f str))))"
 ;