diff --git a/app/src/main/java/com/example/jnicpp/bowling/PosePhaseDetector.kt b/app/src/main/java/com/example/jnicpp/bowling/PosePhaseDetector.kt
index 966914c..64d647d 100644
--- a/app/src/main/java/com/example/jnicpp/bowling/PosePhaseDetector.kt
+++ b/app/src/main/java/com/example/jnicpp/bowling/PosePhaseDetector.kt
@@ -197,14 +197,18 @@ class PosePhaseDetector {
             rightElbowAngleDegrees = angles.rightElbow
         )
 
-        // Identify the next phase we are looking for in the sequence.
+        // Identify the next phase we are looking for in the sequence. The
+        // only BowlingPhase values not already matched above are
+        // BACK_SWING/POWER_STEP (never currentPhase -- see this class's
+        // doc) and FOLLOW_THROUGH, so reaching else always means
+        // FOLLOW_THROUGH: the final phase, nothing to advance to.
         val targetPhase = when (currentPhase) {
             null -> BowlingPhase.STARTING_STANCE
             BowlingPhase.STARTING_STANCE -> BowlingPhase.APPROACH
             BowlingPhase.APPROACH -> BowlingPhase.PUSHAWAY
             BowlingPhase.PUSHAWAY -> BowlingPhase.SLIDE_AND_RELEASE
             BowlingPhase.SLIDE_AND_RELEASE -> BowlingPhase.FOLLOW_THROUGH
-            else -> currentPhase
+            else -> BowlingPhase.FOLLOW_THROUGH
         }
 
         // 1. Check if the user is in the NEXT phase.