diff --git a/src/lean_spec/subspecs/forkchoice/store.py b/src/lean_spec/subspecs/forkchoice/store.py
index 2f48ff13..b840fac0 100644
--- a/src/lean_spec/subspecs/forkchoice/store.py
+++ b/src/lean_spec/subspecs/forkchoice/store.py
@@ -732,7 +732,7 @@ def tick_interval(self, has_proposal: bool) -> "Store":
         """
         # Advance time by one interval
         store = self.model_copy(update={"time": self.time + Uint64(1)})
-        current_interval = store.time % SECONDS_PER_SLOT % INTERVALS_PER_SLOT
+        current_interval = store.time % INTERVALS_PER_SLOT
 
         if current_interval == Uint64(0):
             # Start of slot - process attestations if proposal exists