diff --git a/EKF/optflow_fusion.cpp b/EKF/optflow_fusion.cpp
index a79a5b0a65..45342bc4f9 100644
--- a/EKF/optflow_fusion.cpp
+++ b/EKF/optflow_fusion.cpp
@@ -43,6 +43,7 @@
 #include "ekf.h"
 #include <ecl.h>
 #include <mathlib/mathlib.h>
+#include <cfloat>
 
 void Ekf::fuseOptFlow()
 {
@@ -538,7 +539,7 @@ void Ekf::calcOptFlowBias()
 
 	// if accumulation time differences are not excessive and accumulation time is adequate
 	// compare the optical flow and and navigation rate data and calculate a bias error
-	if ((fabsf(_delta_time_of - _flow_sample_delayed.dt) < 0.1f) && (_delta_time_of > 0.01f)) {
+	if ((fabsf(_delta_time_of - _flow_sample_delayed.dt) < 0.1f) && (_delta_time_of > FLT_EPSILON)) {
 		// calculate a reference angular rate
 		Vector3f reference_body_rate;
 		reference_body_rate = _imu_del_ang_of * (1.0f / _delta_time_of);