diff --git a/build.sh b/build.sh
new file mode 100644
index 00000000..d8032638
--- /dev/null
+++ b/build.sh
@@ -0,0 +1,5 @@
+./scripts/generate-entrypoints.rb ./src/checker.mli > ./src/checkerEntrypoints.ml
+python ./checker_tools/builder/cli.py generate --out src
+./scripts/generate-ligo.sh
+python fix_ligo.py
+./scripts/compile-ligo.rb
diff --git a/checker_tools/client/operations.py b/checker_tools/client/operations.py
index 389c29db..479e05bd 100644
--- a/checker_tools/client/operations.py
+++ b/checker_tools/client/operations.py
@@ -112,7 +112,7 @@ def await_operations(
         )
         # Note: This is only a *minimum* bound.
         block_expected_starting_at = current_block_timestamp.timestamp() + int(
-            tz.shell.blocks[current_level].context.constants()["time_between_blocks"][0]
+            tz.shell.blocks[current_level].context.constants()["minimal_block_delay"][0]
         )
         sleep_for = max(1, block_expected_starting_at - datetime.utcnow().timestamp())
         if sleep_for > MAX_BLOCK_TIME:
diff --git a/fix_ligo.py b/fix_ligo.py
new file mode 100644
index 00000000..4d22f173
--- /dev/null
+++ b/fix_ligo.py
@@ -0,0 +1,31 @@
+import os
+
+
+if __name__ == '__main__':
+    dst_dir = './generated/ligo'
+    files_list = [os.path.join(dst_dir, f) for f in os.listdir(dst_dir) if f.endswith('mligo')]
+    print(f'Found {len(files_list)} files.')
+
+    for file_path in files_list:
+        print(f'Fixing {file_path}.')
+        with open(file_path) as f:
+            initial_text = f.read()
+            fixed_text = initial_text.replace(
+                'Tezos.amount',
+                '(Tezos.get_amount unit)'
+            ).replace(
+                'Tezos.sender',
+                '(Tezos.get_sender unit)'
+            ).replace(
+                'Tezos.level',
+                '(Tezos.get_level unit)'
+            ).replace(
+                'Tezos.now',
+                '(Tezos.get_now unit)'
+            ).replace(
+                'Tezos.self_address',
+                '(Tezos.get_self_address unit)'
+            )
+
+        with open(file_path, 'w') as f:
+            f.write(fixed_text)
diff --git a/src/ligo.mligo b/src/ligo.mligo
index 07c909f9..bb87e8d0 100644
--- a/src/ligo.mligo
+++ b/src/ligo.mligo
@@ -5,7 +5,7 @@
 [@inline] let add_timestamp_int (i: timestamp) (j: int) : timestamp = i + j
 
 [@inline] let sub_int_int (i: int) (j: int) : int = i - j
-[@inline] let sub_tez_tez (i: tez) (j: tez) : tez = i - j
+[@inline] let sub_tez_tez (i: tez) (j: tez) : tez = match i - j with | None -> (failwith "subTezosError") | Some n -> n
 [@inline] let sub_nat_nat (i: nat) (j: nat) : int = i - j
 [@inline] let sub_timestamp_timestamp (i: timestamp) (j: timestamp) : int = i - j