diff --git a/includes/timer.h b/includes/timer.h
index 87f9ddf..5039330 100644
--- a/includes/timer.h
+++ b/includes/timer.h
@@ -3,33 +3,26 @@ extern "C" {
 #endif
 #ifndef _TIMER_H
 #define _TIMER_H
-/* This file defines a simple timer struct, and methods to initialize it,
-and keep track of time elapsed.
+
+#include <stdbool.h>
+
+/* This file defines a simple timer Types, and declares functions to initialize it,
+and keep track of time elapsed. The actual definition of the Timer struct is in timer.c
 It was copied from https://github.com/raysan5/raylib/wiki/Frequently-Asked-Questions#how-do-i-make-a-timer */
 
-typedef struct Timer {
+typedef struct Timer_s {
     double start_time;   // Start time (seconds)
     double lifetime;    // Lifetime (seconds)
 } Timer;
 
-Timer timer_init(double lifetime_secs)
-{
-    Timer timer;
-    timer.start_time = GetTime();
-    timer.lifetime = lifetime_secs;
-    
-    return timer;
-}
+/* Starts a timer for given number of seconds */
+Timer timer_init(double lifetime_secs);
 
-bool timer_done(Timer timer)
-{
-    return GetTime() - timer.start_time >= timer.lifetime;
-}
+/* Returns true when timer finishes, false if not */
+bool timer_done(Timer timer);
 
-double timer_get_elapsed(Timer timer)
-{
-    return GetTime() - timer.start_time;
-}
+/* Returns amount of time elapsed since start of timer */
+double timer_get_elapsed(Timer timer);
 
 #endif
 #ifdef __cplusplus
diff --git a/timer.c b/timer.c
new file mode 100644
index 0000000..15ae432
--- /dev/null
+++ b/timer.c
@@ -0,0 +1,19 @@
+#include <stdbool.h>
+#include "includes/timer.h"
+#include "includes/raygui/raygui.h"
+
+Timer timer_init(double lifetime_secs) {
+    Timer timer;
+    timer.start_time = GetTime();
+    timer.lifetime = lifetime_secs;
+    
+    return timer;
+}
+
+bool timer_done(Timer timer) {
+    return GetTime() - timer.start_time >= timer.lifetime;
+}
+
+double timer_get_elapsed(Timer timer) {
+    return GetTime() - timer.start_time;
+}