diff --git a/zebra-chain/src/history_tree.rs b/zebra-chain/src/history_tree.rs
index 8453adb9..7b133edc 100644
--- a/zebra-chain/src/history_tree.rs
+++ b/zebra-chain/src/history_tree.rs
@@ -200,7 +200,7 @@ impl NonEmptyHistoryTree {
             .expect("block must have coinbase height during contextual verification");
 
         assert!(
-            height - self.current_height == 1,
+            Some(height) == self.current_height + 1,
             "added block with height {:?} but it must be {:?}+1",
             height,
             self.current_height
diff --git a/zebra-chain/src/primitives/zcash_history.rs b/zebra-chain/src/primitives/zcash_history.rs
index f4438faf..5dd4bef6 100644
--- a/zebra-chain/src/primitives/zcash_history.rs
+++ b/zebra-chain/src/primitives/zcash_history.rs
@@ -184,7 +184,7 @@ impl<V: Version> Tree<V> {
         let network_upgrade = NetworkUpgrade::current(self.network, height);
 
         assert!(
-            self.network_upgrade == network_upgrade,
+            network_upgrade == self.network_upgrade,
             "added block from network upgrade {:?} but history tree is restricted to {:?}",
             network_upgrade,
             self.network_upgrade