diff --git a/libraries/DataFlash/LogFile.cpp b/libraries/DataFlash/LogFile.cpp
index 50e2ffbd9c..5591142128 100644
--- a/libraries/DataFlash/LogFile.cpp
+++ b/libraries/DataFlash/LogFile.cpp
@@ -1411,7 +1411,7 @@ void DataFlash_Class::Log_Write_EKF2(AP_AHRS_NavEKF &ahrs, bool optFlowEnabled)
                     rng : (int16_t)(100*rng),
                     innov : (int16_t)(100*innov),
                     sqrtInnovVar : (uint16_t)(100*safe_sqrt(innovVar)),
-                    testRatio : (uint16_t)(100*testRatio),
+                    testRatio : (uint16_t)(100*constrain_float(testRatio,0.0f,650.0f)),
                     beaconPosN : (int16_t)(100*beaconPosNED.x),
                     beaconPosE : (int16_t)(100*beaconPosNED.y),
                     beaconPosD : (int16_t)(100*beaconPosNED.z),
@@ -1739,7 +1739,7 @@ void DataFlash_Class::Log_Write_EKF3(AP_AHRS_NavEKF &ahrs, bool optFlowEnabled)
                 rng : (int16_t)(100*rng),
                 innov : (int16_t)(100*innov),
                 sqrtInnovVar : (uint16_t)(100*sqrtf(innovVar)),
-                testRatio : (uint16_t)(100*testRatio),
+                testRatio : (uint16_t)(100*constrain_float(testRatio,0.0f,650.0f)),
                 beaconPosN : (int16_t)(100*beaconPosNED.x),
                 beaconPosE : (int16_t)(100*beaconPosNED.y),
                 beaconPosD : (int16_t)(100*beaconPosNED.z),