diff --git a/domain/src/main/kotlin/ch/dissem/yaep/domain/Grid.kt b/domain/src/main/kotlin/ch/dissem/yaep/domain/Grid.kt
index 1406973..c59287c 100644
--- a/domain/src/main/kotlin/ch/dissem/yaep/domain/Grid.kt
+++ b/domain/src/main/kotlin/ch/dissem/yaep/domain/Grid.kt
@@ -5,6 +5,9 @@ class Grid(
     val rows: List<GameRow<*>>
 ) : List<GameRow<ItemClass<*>>> by rows as List<GameRow<ItemClass<*>>> {
 
+    val cells: List<GameCell<*>>
+        get() = rows.flatten() as List<GameCell<*>>
+
     fun <C : ItemClass<C>> indexOf(element: C): Int {
         return this[element.companion]
             .indexOfFirst { it.selection?.itemType == element }
@@ -19,14 +22,6 @@ class Grid(
         return this[item.itemType.companion].first { it.selection == item }
     }
 
-    fun anyCell(predicate: (GameCell<ItemClass<*>>) -> Boolean): Boolean {
-        return flatMap { it }.any(predicate)
-    }
-
-    fun allCells(predicate: (GameCell<ItemClass<*>>) -> Boolean): Boolean {
-        return flatMap { it }.all(predicate)
-    }
-
     override fun toString(): String {
         return joinToString("\n") { row ->
             row.joinToString("") { it.selection?.symbol ?: "  " }
diff --git a/domain/src/main/kotlin/ch/dissem/yaep/domain/clues.kt b/domain/src/main/kotlin/ch/dissem/yaep/domain/clues.kt
index 35d8202..5b7ce01 100644
--- a/domain/src/main/kotlin/ch/dissem/yaep/domain/clues.kt
+++ b/domain/src/main/kotlin/ch/dissem/yaep/domain/clues.kt
@@ -107,8 +107,10 @@ class TripletClue<A : ItemClass<A>, B : ItemClass<B>, C : ItemClass<C>>(
                     ia + 1 -> {
                         return if (ic != -1) {
                             ic != ia + 2
-                        } else {
+                        } else if (ia + 2 < grid.size) {
                             !rowC[ia + 2].mayBe(c)
+                        } else {
+                            true
                         }
                     }
 
diff --git a/domain/src/main/kotlin/ch/dissem/yaep/domain/generator.kt b/domain/src/main/kotlin/ch/dissem/yaep/domain/generator.kt
index d7f7a84..ba7b6ef 100644
--- a/domain/src/main/kotlin/ch/dissem/yaep/domain/generator.kt
+++ b/domain/src/main/kotlin/ch/dissem/yaep/domain/generator.kt
@@ -62,10 +62,10 @@ internal fun solve(
     } while (removedOptions)
 
     // If any cell has no items left, the puzzle has no solution.
-    if (grid.anyCell { cell -> cell.options.isEmpty() }) return NO_SOLUTION
+    if (grid.cells.any { cell -> cell.options.isEmpty() }) return NO_SOLUTION
 
     // If all cells have exactly one item left, the puzzle is solved.
-    if (grid.allCells { it.selection != null }) return SOLVABLE
+    if (grid.cells.all { it.selection != null }) return SOLVABLE
 
     // If there are still cells with multiple items, pick one and try each item in turn, then go back to step 2.
     for (i in 0 until grid.size) {
diff --git a/domain/src/test/kotlin/ch/dissem/yaep/domain/GameTest.kt b/domain/src/test/kotlin/ch/dissem/yaep/domain/GameTest.kt
index fd4840d..6488806 100644
--- a/domain/src/test/kotlin/ch/dissem/yaep/domain/GameTest.kt
+++ b/domain/src/test/kotlin/ch/dissem/yaep/domain/GameTest.kt
@@ -9,24 +9,35 @@ import ch.dissem.yaep.domain.Nationality.UKRAINE
 import ch.dissem.yaep.domain.Profession.ASTRONAUT
 import ch.dissem.yaep.domain.Profession.FARMER
 import ch.dissem.yaep.domain.Profession.SOFTWARE_DEV
+import ch.dissem.yaep.domain.PuzzleSolution.SOLVABLE
 import ch.tutteli.atrium.api.fluent.en_GB.feature
+import ch.tutteli.atrium.api.fluent.en_GB.toBeGreaterThan
 import ch.tutteli.atrium.api.fluent.en_GB.toBeLessThan
 import ch.tutteli.atrium.api.fluent.en_GB.toEqual
 import ch.tutteli.atrium.api.verbs.expect
 import kotlin.test.Test
+import kotlin.time.Duration.Companion.seconds
+import kotlin.time.measureTime
 
 class GameTest {
 
     @Test
     fun `ensure generated game is valid`() {
-        val game = generateGame()
+        val game: Game
+        val time = measureTime {
+            game = generateGame()
+        }
         expect(game) {
             feature(Game::areCategoriesValid).toEqual(true)
             feature(Game::areRulesViolated).toEqual(false)
             feature(Game::clues) {
+                feature(List<Clue>::size).toBeGreaterThan(5)
                 feature(List<Clue>::size).toBeLessThan(30)
             }
         }
+        println("Clues: ${game.clues.size}")
+        expect(solve(game.grid, game.clues)).toEqual(SOLVABLE)
+        expect(time).toBeLessThan(1.seconds)
     }
 
     @Test
@@ -73,7 +84,7 @@ class GameTest {
             )
         )
 
-        expect(solve(game.grid, game.clues)).toEqual(PuzzleSolution.SOLVABLE)
+        expect(solve(game.grid, game.clues)).toEqual(SOLVABLE)
     }
 
 }
\ No newline at end of file