diff --git a/ArduCopter/mode_acro.cpp b/ArduCopter/mode_acro.cpp
index 32f23bd910..0f0e61aa6d 100644
--- a/ArduCopter/mode_acro.cpp
+++ b/ArduCopter/mode_acro.cpp
@@ -111,7 +111,7 @@ void ModeAcro::get_pilot_desired_angle_rates(int16_t roll_in, int16_t pitch_in,
     }
 
     // range check expo
-    g.acro_rp_expo = constrain_float(g.acro_rp_expo, 0.0f, 1.0f);
+    g.acro_rp_expo = constrain_float(g.acro_rp_expo, -0.5f, 1.0f);
     
     // calculate roll, pitch rate requests
     if (is_zero(g.acro_rp_expo)) {