diff --git a/app/src/main/java/com/jsjdesigns/poker/ActionButtons.kt b/app/src/main/java/com/jsjdesigns/poker/ActionButtons.kt
index 856014f..1674464 100644
--- a/app/src/main/java/com/jsjdesigns/poker/ActionButtons.kt
+++ b/app/src/main/java/com/jsjdesigns/poker/ActionButtons.kt
@@ -11,6 +11,8 @@ import com.jsjdesigns.poker.game.DecisionOffer
 data class ActionButtons(
     val showFold: Boolean,
     val checkOrCallLabel: String,
+    /** What calling actually costs: the engine clamps a call to the stack. */
+    val effectiveCall: Int,
     val showRaise: Boolean,
     /** False when there is exactly one legal raise size, so a slider is pointless. */
     val showSlider: Boolean,
@@ -29,10 +31,20 @@ fun buttonsFor(offer: DecisionOffer): ActionButtons {
     val low = if (shoveOnly) offer.maxRaiseTo else offer.minRaiseTo
     val high = offer.maxRaiseTo
 
+    // Facing more than you have left is a call for your whole stack: the engine
+    // clamps the commitment, so quoting the full price promises something the
+    // player cannot pay and does not owe.
+    val effectiveCall = minOf(offer.toCall, offer.stack)
+
     return ActionButtons(
         // Folding a free hand is never correct, so don't invite an accidental muck.
         showFold = !offer.canCheck,
-        checkOrCallLabel = if (offer.canCheck) "Check" else "Call ${offer.toCall}",
+        checkOrCallLabel = when {
+            offer.canCheck -> "Check"
+            effectiveCall >= offer.stack -> "All in $effectiveCall"
+            else -> "Call $effectiveCall"
+        },
+        effectiveCall = effectiveCall,
         showRaise = offer.canRaise,
         showSlider = high > low,
         sliderMin = low,
diff --git a/app/src/main/java/com/jsjdesigns/poker/PokerViewModel.kt b/app/src/main/java/com/jsjdesigns/poker/PokerViewModel.kt
index 21ecba4..844cd48 100644
--- a/app/src/main/java/com/jsjdesigns/poker/PokerViewModel.kt
+++ b/app/src/main/java/com/jsjdesigns/poker/PokerViewModel.kt
@@ -153,7 +153,10 @@ class PokerViewModel : ViewModel() {
     fun checkOrCall(token: Long) {
         val o = offer.value ?: return
         if (o.token != token) return
-        submit(token, if (o.canCheck) Action(ActionType.CHECK) else Action(ActionType.CALL, o.toCall))
+        // Send what the button promised. The engine would clamp an oversized call
+        // anyway, but the submitted action should not disagree with the label.
+        val cost = minOf(o.toCall, o.stack)
+        submit(token, if (o.canCheck) Action(ActionType.CHECK) else Action(ActionType.CALL, cost))
     }
 
     fun raiseTo(token: Long, amount: Int) = submit(token, Action(ActionType.RAISE, amount))
diff --git a/app/src/test/java/com/jsjdesigns/poker/ActionButtonsTest.kt b/app/src/test/java/com/jsjdesigns/poker/ActionButtonsTest.kt
index 106d07c..6b7e5a6 100644
--- a/app/src/test/java/com/jsjdesigns/poker/ActionButtonsTest.kt
+++ b/app/src/test/java/com/jsjdesigns/poker/ActionButtonsTest.kt
@@ -97,3 +97,48 @@ class ActionButtonsTest {
         assertEquals("All in", raiseLabel(b, 500))
     }
 }
+
+class CallCostTest {
+
+    private fun offer(toCall: Int, stack: Int) = DecisionOffer(
+        token = 1L,
+        handNumber = 1,
+        street = Street.RIVER,
+        seat = 0,
+        hole = listOf(0, 1),
+        board = emptyList(),
+        pot = 100,
+        toCall = toCall,
+        minRaiseTo = 999,
+        maxRaiseTo = stack,
+        stack = stack,
+        canCheck = false,
+        canRaise = false,
+    )
+
+    /**
+     * Facing more than you have left is a call for your whole stack; the engine
+     * clamps the commitment. Quoting the full price promised a payment the player
+     * could not make and did not owe.
+     */
+    @Test
+    fun `facing more than the stack is labelled as an all in for the stack`() {
+        val b = buttonsFor(offer(toCall = 35, stack = 20))
+        assertEquals("All in 20", b.checkOrCallLabel)
+        assertEquals(20, b.effectiveCall)
+    }
+
+    @Test
+    fun `calling exactly the stack is also an all in`() {
+        val b = buttonsFor(offer(toCall = 20, stack = 20))
+        assertEquals("All in 20", b.checkOrCallLabel)
+        assertEquals(20, b.effectiveCall)
+    }
+
+    @Test
+    fun `an affordable call quotes the real price`() {
+        val b = buttonsFor(offer(toCall = 35, stack = 500))
+        assertEquals("Call 35", b.checkOrCallLabel)
+        assertEquals(35, b.effectiveCall)
+    }
+}