diff --git a/wpilibc/src/main/native/include/frc/OnboardIMU.h b/wpilibc/src/main/native/include/frc/OnboardIMU.h
index f61c5b921a..067fbf8c32 100644
--- a/wpilibc/src/main/native/include/frc/OnboardIMU.h
+++ b/wpilibc/src/main/native/include/frc/OnboardIMU.h
@@ -22,11 +22,13 @@ class OnboardIMU {
    * A mount orientation of SystemCore
    */
   enum MountOrientation {
-    /** Flat */
+    /** Flat (mounted parallel to the ground). */
     kFlat,
-    /** Landscape */
+    /** Landscape (vertically mounted with long edge of SystemCore parallel to
+       the ground). */
     kLandscape,
-    /** Portrait */
+    /** Portrait (vertically mounted with the short edge of SystemCore parallel
+       to the ground). */
     kPortrait
   };
 
diff --git a/wpilibj/src/main/java/edu/wpi/first/wpilibj/OnboardIMU.java b/wpilibj/src/main/java/edu/wpi/first/wpilibj/OnboardIMU.java
index 8e36ac877e..ade58b7d99 100644
--- a/wpilibj/src/main/java/edu/wpi/first/wpilibj/OnboardIMU.java
+++ b/wpilibj/src/main/java/edu/wpi/first/wpilibj/OnboardIMU.java
@@ -13,11 +13,11 @@ import edu.wpi.first.math.geometry.Rotation3d;
 public class OnboardIMU {
   /** A mount orientation of SystemCore. */
   public enum MountOrientation {
-    /** Flat. */
+    /** Flat (mounted parallel to the ground). */
     kFlat,
-    /** Landscape. */
+    /** Landscape (vertically mounted with long edge of SystemCore parallel to the ground). */
     kLandscape,
-    /** Portrait. */
+    /** Portrait (vertically mounted with the short edge of SystemCore parallel to the ground). */
     kPortrait
   }