diff --git a/libraries/AP_NavEKF/AP_NavEKF_Source.cpp b/libraries/AP_NavEKF/AP_NavEKF_Source.cpp
index 066a7c496a..909ee63c89 100644
--- a/libraries/AP_NavEKF/AP_NavEKF_Source.cpp
+++ b/libraries/AP_NavEKF/AP_NavEKF_Source.cpp
@@ -52,7 +52,7 @@ const AP_Param::GroupInfo AP_NavEKF_Source::var_info[] = {
     // @Param: 1_YAW
     // @DisplayName: Yaw Source
     // @Description: Yaw Source
-    // @Values: 0:None, 1:Compass, 2:External, 3:External with Compass Fallback, 6:ExternalNav, 8:GSF
+    // @Values: 0:None, 1:Compass, 2:GPS, 3:GPS with Compass Fallback, 6:ExternalNav, 8:GSF
     // @User: Advanced
     AP_GROUPINFO("1_YAW", 5, AP_NavEKF_Source, _source_set[0].yaw, (int8_t)AP_NavEKF_Source::SourceYaw::COMPASS),
 
@@ -88,7 +88,7 @@ const AP_Param::GroupInfo AP_NavEKF_Source::var_info[] = {
     // @Param: 2_YAW
     // @DisplayName: Yaw Source (Secondary)
     // @Description: Yaw Source (Secondary)
-    // @Values: 0:None, 1:Compass, 2:External, 3:External with Compass Fallback, 6:ExternalNav, 8:GSF
+    // @Values: 0:None, 1:Compass, 2:GPS, 3:GPS with Compass Fallback, 6:ExternalNav, 8:GSF
     // @User: Advanced
     AP_GROUPINFO("2_YAW", 10, AP_NavEKF_Source, _source_set[1].yaw, (int8_t)AP_NavEKF_Source::SourceYaw::NONE),
 #endif
@@ -125,7 +125,7 @@ const AP_Param::GroupInfo AP_NavEKF_Source::var_info[] = {
     // @Param: 3_YAW
     // @DisplayName: Yaw Source (Tertiary)
     // @Description: Yaw Source (Tertiary)
-    // @Values: 0:None, 1:Compass, 2:External, 3:External with Compass Fallback, 6:ExternalNav, 8:GSF
+    // @Values: 0:None, 1:Compass, 2:GPS, 3:GPS with Compass Fallback, 6:ExternalNav, 8:GSF
     // @User: Advanced
     AP_GROUPINFO("3_YAW", 15, AP_NavEKF_Source, _source_set[2].yaw, (int8_t)AP_NavEKF_Source::SourceYaw::NONE),
 #endif
@@ -404,13 +404,13 @@ bool AP_NavEKF_Source::pre_arm_check(char *failure_msg, uint8_t failure_msg_len)
         // check yaw
         switch ((SourceYaw)_source_set[i].yaw.get()) {
         case SourceYaw::NONE:
-        case SourceYaw::EXTERNAL:
+        case SourceYaw::GPS:
             // valid yaw value
             break;
         case SourceYaw::COMPASS:
             // skip compass check for easier user setup of compass-less operation
             break;
-        case SourceYaw::EXTERNAL_COMPASS_FALLBACK:
+        case SourceYaw::GPS_COMPASS_FALLBACK:
             compass_required = true;
             break;
         case SourceYaw::EXTNAV:
@@ -514,14 +514,14 @@ bool AP_NavEKF_Source::wheel_encoder_enabled(void) const
     return false;
 }
 
-// return true if ext yaw is enabled on any source
-bool AP_NavEKF_Source::ext_yaw_enabled(void) const
+// return true if GPS yaw is enabled on any source
+bool AP_NavEKF_Source::gps_yaw_enabled(void) const
 {
     for (uint8_t i=0; i<AP_NAKEKF_SOURCE_SET_MAX; i++) {
         const auto &src = _source_set[i];
         const SourceYaw yaw = SourceYaw(src.yaw.get());
-        if (yaw == SourceYaw::EXTERNAL ||
-            yaw == SourceYaw::EXTERNAL_COMPASS_FALLBACK) {
+        if (yaw == SourceYaw::GPS ||
+            yaw == SourceYaw::GPS_COMPASS_FALLBACK) {
             return true;
         }
     }
diff --git a/libraries/AP_NavEKF/AP_NavEKF_Source.h b/libraries/AP_NavEKF/AP_NavEKF_Source.h
index 2c394c8a57..dc3a1b7d94 100644
--- a/libraries/AP_NavEKF/AP_NavEKF_Source.h
+++ b/libraries/AP_NavEKF/AP_NavEKF_Source.h
@@ -40,8 +40,8 @@ public:
     enum class SourceYaw : uint8_t {
         NONE = 0,
         COMPASS = 1,
-        EXTERNAL = 2,
-        EXTERNAL_COMPASS_FALLBACK = 3,
+        GPS = 2,
+        GPS_COMPASS_FALLBACK = 3,
         EXTNAV = 6,
         GSF = 8
     };
@@ -95,8 +95,8 @@ public:
     // return true if ext nav is enabled on any source
     bool ext_nav_enabled(void) const;
 
-    // return true if ext yaw is enabled on any source
-    bool ext_yaw_enabled(void) const;
+    // return true if GPS yaw is enabled on any source
+    bool gps_yaw_enabled(void) const;
 
     // return true if wheel encoder is enabled on any source
     bool wheel_encoder_enabled(void) const;