diff --git a/flap/src/hopix/hopixTypechecker.ml b/flap/src/hopix/hopixTypechecker.ml
index 694c74f..594ace2 100644
--- a/flap/src/hopix/hopixTypechecker.ml
+++ b/flap/src/hopix/hopixTypechecker.ml
@@ -230,7 +230,12 @@ and synth_while
   :  HopixTypes.typing_environment -> expression Position.located
   -> expression Position.located -> HopixTypes.aty
   =
-  fun tenv ecase expr -> failwith "Students! This is your job! (synth_while)"
+  fun tenv ecase c ->
+  let ecasety = synth_expression tenv ecase in
+  check_equal_types ecase.position ~expected:ecasety ~given:HopixTypes.hbool;
+  let exprty = synth_expression tenv c in
+  check_equal_types c.position ~expected:exprty ~given:HopixTypes.hunit;
+  HopixTypes.hunit
 
 and synth_for
   :  HopixTypes.typing_environment -> identifier Position.located