diff --git a/libraries/AP_NavEKF2/AP_NavEKF2_OptFlowFusion.cpp b/libraries/AP_NavEKF2/AP_NavEKF2_OptFlowFusion.cpp
index aa13ad939e..a13910e43a 100644
--- a/libraries/AP_NavEKF2/AP_NavEKF2_OptFlowFusion.cpp
+++ b/libraries/AP_NavEKF2/AP_NavEKF2_OptFlowFusion.cpp
@@ -85,7 +85,7 @@ void NavEKF2_core::EstimateTerrainOffset()
 
     // don't fuse flow data if LOS rate is misaligned, without GPS, or insufficient velocity, as it is poorly observable
     // don't fuse flow data if it exceeds validity limits
-    // don't update terrain offset if grpund is being used as the zero height datum in the main filter
+    // don't update terrain offset if ground is being used as the zero height datum in the main filter
     bool cantFuseFlowData = ((frontend->_flowUse != FLOW_USE_TERRAIN)
     || gpsNotAvailable 
     || PV_AidingMode == AID_RELATIVE