diff --git a/libraries/AP_Math/quaternion.cpp b/libraries/AP_Math/quaternion.cpp
index bdf4b6c920..7a04dcbeaa 100644
--- a/libraries/AP_Math/quaternion.cpp
+++ b/libraries/AP_Math/quaternion.cpp
@@ -189,6 +189,7 @@ void QuaternionT<T>::from_rotation(enum Rotation rotation)
         return;
 
     case ROTATION_ROLL_180_YAW_90:
+    case ROTATION_PITCH_180_YAW_270:
         q1 = q4 = 0;
         q2 = q3 = HALF_SQRT_2;
         return;
@@ -211,6 +212,7 @@ void QuaternionT<T>::from_rotation(enum Rotation rotation)
         return;
 
     case ROTATION_ROLL_180_YAW_270:
+    case ROTATION_PITCH_180_YAW_90:
         q1 = q4 = 0;
         q2 = -HALF_SQRT_2;
         q3 = HALF_SQRT_2;
@@ -279,17 +281,6 @@ void QuaternionT<T>::from_rotation(enum Rotation rotation)
         q3 = -HALF_SQRT_2;
         return;
 
-    case ROTATION_PITCH_180_YAW_90:
-        q1 = q4 = 0;
-        q2 = -HALF_SQRT_2;
-        q3 = HALF_SQRT_2;
-        return;
-
-    case ROTATION_PITCH_180_YAW_270:
-        q1 = q4 = 0;
-        q2 = q3 = HALF_SQRT_2;
-        return;
-
     case ROTATION_ROLL_90_PITCH_90:
         q1 = q2 = q3 = -0.5f;
         q4 = 0.5f;
diff --git a/libraries/AP_Math/rotations.h b/libraries/AP_Math/rotations.h
index 519c685a9d..6a232d32c0 100644
--- a/libraries/AP_Math/rotations.h
+++ b/libraries/AP_Math/rotations.h
@@ -51,8 +51,8 @@ enum Rotation : uint8_t {
     ROTATION_ROLL_270_YAW_135    = 23,
     ROTATION_PITCH_90            = 24,
     ROTATION_PITCH_270           = 25,
-    ROTATION_PITCH_180_YAW_90    = 26,
-    ROTATION_PITCH_180_YAW_270   = 27,
+    ROTATION_PITCH_180_YAW_90    = 26, // same as ROTATION_ROLL_180_YAW_270
+    ROTATION_PITCH_180_YAW_270   = 27, // same as ROTATION_ROLL_180_YAW_90
     ROTATION_ROLL_90_PITCH_90    = 28,
     ROTATION_ROLL_180_PITCH_90   = 29,
     ROTATION_ROLL_270_PITCH_90   = 30,
diff --git a/libraries/AP_Math/vector3.cpp b/libraries/AP_Math/vector3.cpp
index 55c3cfe6f5..cee78b9801 100644
--- a/libraries/AP_Math/vector3.cpp
+++ b/libraries/AP_Math/vector3.cpp
@@ -75,7 +75,8 @@ void Vector3<T>::rotate(enum Rotation rotation)
         x = tmp; z = -z;
         return;
     }
-    case ROTATION_ROLL_180_YAW_90: {
+    case ROTATION_ROLL_180_YAW_90:
+    case ROTATION_PITCH_180_YAW_270: {
         tmp = x; x = y; y = tmp; z = -z;
         return;
     }
@@ -95,7 +96,8 @@ void Vector3<T>::rotate(enum Rotation rotation)
         x = tmp; z = -z;
         return;
     }
-    case ROTATION_ROLL_180_YAW_270: {
+    case ROTATION_ROLL_180_YAW_270: 
+    case ROTATION_PITCH_180_YAW_90: {
         tmp = x; x = -y; y = -tmp; z = -z;
         return;
     }
@@ -159,16 +161,6 @@ void Vector3<T>::rotate(enum Rotation rotation)
         tmp = z; z = x; x = -tmp;
         return;
     }
-    case ROTATION_PITCH_180_YAW_90: {
-        z = -z;
-        tmp = -x; x = -y; y = tmp;
-        return;
-    }
-    case ROTATION_PITCH_180_YAW_270: {
-        x = -x; z = -z;
-        tmp = x; x = y; y = -tmp;
-        return;
-    }
     case ROTATION_ROLL_90_PITCH_90: {
         tmp = z; z = y; y = -tmp;
         tmp = z; z = -x; x = tmp;