diff --git a/src/env.c b/src/env.c
index c331b15..d15f4ee 100644
--- a/src/env.c
+++ b/src/env.c
@@ -131,7 +131,7 @@ struct Environment envForLambda(const Object* params, const Object* arguments, i
     // Evaluate the `argument` list
     const Object* param = params->list;
     const Object* argument = arguments;
-    for (int i = 0; i < paramCount && param; i++) {
+    for (; param; param = param->forward) {
         const char* paramName = param->string;
         if (paramName[0] == '.' && paramName[1] == '.' && paramName[2] == '.' && paramName[3] != '\0') {
             paramName = &paramName[3];
@@ -144,6 +144,9 @@ struct Environment envForLambda(const Object* params, const Object* arguments, i
             cleanObject(&varargs);
             break;
         }
+        if (!argument) {
+            break;
+        }
 
         Object newEnvObj = eval(argument, outer);
 
@@ -151,8 +154,7 @@ struct Environment envForLambda(const Object* params, const Object* arguments, i
 
         cleanObject(&newEnvObj);
 
-        argument = argument ? argument->forward : NULL;
-        param = param->forward;
+        argument = argument->forward;
     }
     env.outer = outer;
 
@@ -254,7 +256,8 @@ struct Environment defaultEnv()
         pf(help),
         pf(buildHashTable),
         pf(addToHashTable),
-        pf(getFromHashTable)
+        pf(getFromHashTable),
+        pf(randomO)
 #endif
     };
 
diff --git a/src/examples/lib.pbl b/src/examples/lib.pbl
index bdee7c2..8454cf0 100644
--- a/src/examples/lib.pbl
+++ b/src/examples/lib.pbl
@@ -174,6 +174,14 @@
   (eval (rf file-name))
 )))
 
+(def any-in (fn (list f)
+  (> (len (fil f list)) 0)
+))
+
+(def none-in (fn (list f)
+  (not (any-in list f))
+))
+
 (def startsWith (fn (text pattern) (
   (matches text (cat pattern "*"))
 )))
@@ -184,4 +192,4 @@
 
 (def endsWith (fn (text pattern) (
   (matches text (cat "*" pattern))
-)))
\ No newline at end of file
+)))
diff --git a/src/examples/tic-tac-toe.pbl b/src/examples/tic-tac-toe.pbl
index af24434..db54b46 100755
--- a/src/examples/tic-tac-toe.pbl
+++ b/src/examples/tic-tac-toe.pbl
@@ -6,48 +6,65 @@
   " "  " "  " "
 ))
 
+(def is-empty (fn (tile) (= " " tile)))
+
 (def print-board (fn (board) (
   (sys "clear")
   (def '(a b c
          d e f
          g h i) board)
-  (prnl (cat " " a " | " b " | " c))
-  (prnl "-----------")
-  (prnl (cat " " d " | " e " | " f))
-  (prnl "-----------")
-  (prnl (cat " " g " | " h " | " i))
+  (prnl)
+  (prnl (cat "  " a " | " b " | " c))
+  (prnl " -----------")
+  (prnl (cat "  " d " | " e " | " f))
+  (prnl " -----------")
+  (prnl (cat "  " g " | " h " | " i))
 )))
 
-(def do-move (fn (board player) (
-  (def input (inp))
+(def do-move (fn (board player warn) (
+  (prnl)
+  (if warn (prnl "You can't go there!") ())
+  (prnl "Your turn, " player "!")
+  (prnl "Where do you want to play?")
+  (def input (inp "1-9: "))
   (def spot (eval input))
   (def i 0)
-  (map (fn (piece) (
-    (set i (+ 1 i))
-    (if (= i spot) player piece)
-  )) board)
+  (if (& (is-empty (at (- spot 1) board)) (> spot 0) (< spot 10))
+    (map (fn (piece) (
+      (set i (+ 1 i))
+      (if (= i spot) player piece)
+    )) board)
+    (
+      (print-board board)
+      (do-move board player T)
+    )
+  )
 )))
 
-(def winning-row (fn (row) (
+(def is-winning-row (fn (row) (
   (def '(a b c) row)
-  (& (not (= " " a)) (= a b c))
+  (& (not (is-empty a)) (= a b c))
 )))
 
+(def is-full-board (fn (board)
+  (none-in board is-empty)
+))
+
 (def get-winner (fn (board) (
-  (sys "clear")
   (def '(a b c
          d e f
          g h i) board)
-  (if (winning-row (a b c)) a
-  (if (winning-row (d e f)) d
-  (if (winning-row (g h i)) g
-  (if (winning-row (a d g)) a
-  (if (winning-row (b e h)) b
-  (if (winning-row (c f i)) c
-  (if (winning-row (a e i)) a
-  (if (winning-row (c e g)) c
+  (if (is-winning-row (a b c)) a
+  (if (is-winning-row (d e f)) d
+  (if (is-winning-row (g h i)) g
+  (if (is-winning-row (a d g)) a
+  (if (is-winning-row (b e h)) b
+  (if (is-winning-row (c f i)) c
+  (if (is-winning-row (a e i)) a
+  (if (is-winning-row (c e g)) c
+  (if (is-full-board board) "Nobody"
   " "
-  ))))))))
+  )))))))))
 )))
 
 (def next-player (fn (current) (
@@ -55,15 +72,15 @@
 )))
 
 (def game (fn (board player) (
-  (if (= " " (get-winner board)) (
-    (print-board board)
-    (def b (do-move board player))
+  (print-board board)
+  (def winner (get-winner board))
+  (if (is-empty winner) (
+    (def b (do-move board player F))
     (game b (next-player player))
   ) (
-    (print-board board)
-    (prnl "")
-    (prnl "Game over! " (next-player player) " wins!")
+    (prnl)
+    (prnl "Game over! " winner " wins!")
   ))
 )))
 
-(game empty-board "X")
+(game empty-board (if (= 0 (rand 2)) "X" "O"))
diff --git a/src/pebblisp.h b/src/pebblisp.h
index db703a8..8169afc 100644
--- a/src/pebblisp.h
+++ b/src/pebblisp.h
@@ -49,6 +49,10 @@ Object typeCheck(const char* funcName, Object* params, int length,
 if (FAILED) { \
     return ERROR; \
 }
+#define verifyTypes(FUNC, TYPE_CHECKS) int FAILED; Object ERROR = typeCheck(FUNC ## Symbol, params, length, TYPE_CHECKS, length, &FAILED); \
+if (FAILED) { \
+    return ERROR; \
+}
 #else
 #define checkTypes(FUNC) ;
 #endif
diff --git a/src/plfunc/pc.c b/src/plfunc/pc.c
index 3953b68..3e3f70d 100644
--- a/src/plfunc/pc.c
+++ b/src/plfunc/pc.c
@@ -86,4 +86,20 @@ Object getEnvVar(Object* params, unused int length, unused struct Environment* e
     }
     return stringFromSlice("", 0);
 }
+
+#include <time.h>
+int initializedRand = 0;
+Object randomO(Object* params, unused int length, unused struct Environment* env)
+{
+    if (!initializedRand) {
+        srand(time(0));
+        initializedRand = 1;
+    }
+    int num = rand();
+    if (length > 0 && params[0].type == TYPE_NUMBER) {
+        num = num % params[0].number;
+    }
+    return numberObject(num);
+}
+
 #endif // STANDALONE
\ No newline at end of file
diff --git a/src/plfunc/pc.h b/src/plfunc/pc.h
index 9ea974f..fcbed79 100644
--- a/src/plfunc/pc.h
+++ b/src/plfunc/pc.h
@@ -60,6 +60,12 @@ tfn(getEnvVar, "env",
     "(env HOME) => /home/sagevaillancourt"
 );
 
+tfn(randomO, "rand",
+    ({ returns(isNumber) }),
+    "Returns a semi-random integer\n"
+    "(rand) => 2394568"
+);
+
 #endif //PEBBLISP_PC_H
 
 #endif // STANDALONE
diff --git a/src/tests.sh b/src/tests.sh
index c56f979..dc569e3 100755
--- a/src/tests.sh
+++ b/src/tests.sh
@@ -75,7 +75,9 @@ check() {
     fi
 
 
+    local expected="$3"
     if [ "$3" == "$regex" ]; then
+        expected="$4"
         if [[ "$output" =~ ^$4$ ]]; then
             pass "$1" $exit_code
             return
@@ -86,7 +88,7 @@ check() {
     fi
 
     fail "$1" "$2"
-    FAIL_OUTPUT="${FAIL_OUTPUT}\n    expected '$3' but received '$output'\n"
+    FAIL_OUTPUT="${FAIL_OUTPUT}\n    expected '$expected' but received '$output'\n"
 }
 
 echo "::SHELL TESTS::"