diff --git a/ham.asd b/ham.asd
index cb1c6f0..a341b57 100644
--- a/ham.asd
+++ b/ham.asd
@@ -20,6 +20,6 @@
   :description "A framework for creating physics simulations"
   :depends-on (:sdl2 :maxima :maxima-interface)
   :components ((:file "package")
-			   (:file "drawing" :depends-on ("package"))
-			   (:file "physics-compiler" :depends-on ("package"))
-			   (:file "simulation" :depends-on ("package" "drawing"))))
+               (:file "drawing" :depends-on ("package"))
+               (:file "physics-compiler" :depends-on ("package"))
+               (:file "simulation" :depends-on ("package" "drawing"))))
diff --git a/physics-compiler.lisp b/physics-compiler.lisp
index 00db9e7..0de5f60 100644
--- a/physics-compiler.lisp
+++ b/physics-compiler.lisp
@@ -73,8 +73,8 @@
 
 (defun update-body (result coords params)
   (let ((vars (append coords (mapcar #'momentum-symbol coords))))
-	`(let (,@(mapcar (lambda (s) `(,s (getf params ',s))) (keys params))
-		   ,@(mapcar (lambda (s) `(,s (getf state ',s))) vars))
+    `(let (,@(mapcar (lambda (s) `(,s (getf params ',s))) (keys params))
+           ,@(mapcar (lambda (s) `(,s (getf state ',s))) vars))
 	   ,@(update-logic result coords)
 	   (list ,@(flatten
 				(mapcar (lambda (s) (list `',s s))
diff --git a/simulation.lisp b/simulation.lisp
index e19e5e7..710db0b 100644
--- a/simulation.lisp
+++ b/simulation.lisp
@@ -20,35 +20,35 @@
 (defmethod run ((sim simulation))
   (sdl2:make-this-thread-main
    (lambda ()
-	 (with-slots (width height running) sim
-	   (with-graphics-context (ctx :width width :height height)
-		 (loop while running do
-		   (update sim (/ 1.0 60.0))	; assume 60 Hz
-		   (let ((frame (render sim)))
-			 (display-frame ctx frame))))))))
+     (with-slots (width height running) sim
+       (with-graphics-context (ctx :width width :height height)
+         (loop while running do
+           (update sim (/ 1.0 60.0))    ; assume 60 Hz
+           (let ((frame (render sim)))
+             (display-frame ctx frame))))))))
 
 (defmethod start ((sim simulation))
   (with-slots (running simulation-thread) sim
-	(setf running t)
-	(setf simulation-thread
-		  (sb-thread:make-thread (lambda () (run sim))
-								 :name "ham-simulation-thread"))))
+    (setf running t)
+    (setf simulation-thread
+          (sb-thread:make-thread (lambda () (run sim))
+                                 :name "ham-simulation-thread"))))
 
 (defmethod stop ((sim simulation))
   (with-slots (running simulation-thread) sim
-	(setf running nil)
-	(sb-thread:join-thread simulation-thread)))
+    (setf running nil)
+    (sb-thread:join-thread simulation-thread)))
 
 (defmacro define-simulation (name &key lagrangian coords render start params)
   `(progn
-	 (defclass ,name (simulation)
-	   ()
-	   (:default-initargs :start ',start :params ',params))
-	 (defmethod update ((sim ,name) dt)
-	   (with-slots (state params) sim
-		 (setf state ,(let ((eqns (hamilton-eqns lagrangian coords)))
-						(update-body eqns coords params)))))
-	 (defmethod render ((sim ,name))
-	   (with-slots (state) sim
-		 (let ,(mapcar (lambda (q) `(,q (getf state ',q))) coords)
-		   ,render)))))
+     (defclass ,name (simulation)
+       ()
+       (:default-initargs :start ',start :params ',params))
+     (defmethod update ((sim ,name) dt)
+       (with-slots (state params) sim
+         (setf state ,(let ((eqns (hamilton-eqns lagrangian coords)))
+                        (update-body eqns coords params)))))
+     (defmethod render ((sim ,name))
+       (with-slots (state) sim
+         (let ,(mapcar (lambda (q) `(,q (getf state ',q))) coords)
+           ,render)))))