diff --git a/src/main/flight/imu.c b/src/main/flight/imu.c
index 60fe40d33d..442c47c328 100644
--- a/src/main/flight/imu.c
+++ b/src/main/flight/imu.c
@@ -77,7 +77,7 @@ static bool imuUpdated = false;
 // the limit (in degrees/second) beyond which we stop integrating
 // omega_I. At larger spin rates the DCM PI controller can get 'dizzy'
 // which results in false gyro drift. See
-// http://gentlenav.googlecode.com/files/fastRotations.pdf
+// https://drive.google.com/file/d/0ByvTkVQo3tqXQUVCVUNyZEgtRGs/view?usp=sharing&resourcekey=0-Mo4254cxdWWx2Y4mGN78Zw
 
 #define SPIN_RATE_LIMIT 20