diff --git a/libraries/AP_Baro/AP_Baro.cpp b/libraries/AP_Baro/AP_Baro.cpp
index edc1da5c2f..804b5572b5 100644
--- a/libraries/AP_Baro/AP_Baro.cpp
+++ b/libraries/AP_Baro/AP_Baro.cpp
@@ -319,7 +319,11 @@ float AP_Baro::get_EAS2TAS(void)
     // provides a more consistent reading then trying to estimate a complete
     // ISA model atmosphere
     float tempK = get_ground_temperature() + C_TO_KELVIN - ISA_LAPSE_RATE * altitude;
-    _EAS2TAS = safe_sqrt(SSL_AIR_DENSITY / ((float)get_pressure() / (ISA_GAS_CONSTANT * tempK)));
+    const float eas2tas_squared = SSL_AIR_DENSITY / ((float)get_pressure() / (ISA_GAS_CONSTANT * tempK));
+    if (!is_positive(eas2tas_squared)) {
+        return 1.0;
+    }
+    _EAS2TAS = sqrtf(eas2tas_squared);
     _last_altitude_EAS2TAS = altitude;
     return _EAS2TAS;
 }