diff --git a/.github/workflows/linters.yml b/.github/workflows/linters.yml
index 56ef7bc..cd6f8ea 100644
--- a/.github/workflows/linters.yml
+++ b/.github/workflows/linters.yml
@@ -27,7 +27,13 @@ jobs:
           restore-keys: ${{ runner.os }}-shards-
 
       - name: Install shards
-        run: shards update
+        run: shards install
+
+      - name: Set up bin dir
+        run: mkdir -p bin
+
+      - name: Build ameba
+        run: crystal build -o bin/ameba lib/ameba/bin/ameba.cr
 
       - name: Run linter
         run: bin/ameba
diff --git a/.github/workflows/tests.yml b/.github/workflows/tests.yml
index b155602..83e1c23 100644
--- a/.github/workflows/tests.yml
+++ b/.github/workflows/tests.yml
@@ -37,7 +37,7 @@ jobs:
           restore-keys: ${{ runner.os }}-shards-
 
       - name: Install shards
-        run: shards update
+        run: shards install
 
       - name: Run tests
         run: crystal spec --verbose
diff --git a/README.md b/README.md
index 01b6b08..20f3720 100644
--- a/README.md
+++ b/README.md
@@ -305,6 +305,18 @@ Format the code:
 crystal tool format
 ```
 
+Build ameba:
+
+```
+crystal build -o bin/ameba lib/ameba/bin/ameba.cr
+```
+
+Run ameba:
+
+```
+bin/ameba
+```
+
 ### Guidelines
 
 - Keep the public interface small. Anything that doesn't have to be public, should explicitly be marked as protected or
diff --git a/shard.lock b/shard.lock
index 29bd507..7d59e41 100644
--- a/shard.lock
+++ b/shard.lock
@@ -2,7 +2,7 @@ version: 2.0
 shards:
   ameba:
     git: https://github.com/crystal-ameba/ameba.git
-    version: 1.5.0
+    version: 1.7.0
 
   db:
     git: https://github.com/crystal-lang/crystal-db.git
@@ -10,5 +10,5 @@ shards:
 
   redis:
     git: https://github.com/jgaskins/redis.git
-    version: 0.15.1
+    version: 0.15.3
 
diff --git a/shard.yml b/shard.yml
index bf2d7fd..41c85c7 100644
--- a/shard.yml
+++ b/shard.yml
@@ -5,7 +5,7 @@ authors:
   - Florin Lipan <florinlipan@gmail.com>
   - Rodrigo Pinto <contato@rodrigopinto.me>
 
-crystal: "1.0.0, < 2.0.0"
+crystal: ">= 1.0.0, < 2.0.0"
 
 dependencies:
   redis:
@@ -15,4 +15,4 @@ dependencies:
 development_dependencies:
   ameba:
     github: crystal-ameba/ameba
-    version: ~> 1.5.0
+    version: ~> 1.7.0
diff --git a/src/defense/memory_store.cr b/src/defense/memory_store.cr
index bbe8cee..02210cd 100644
--- a/src/defense/memory_store.cr
+++ b/src/defense/memory_store.cr
@@ -23,7 +23,7 @@ module Defense
       @data.has_key?(key) && @data[key]["expires_at"] > Time.utc.to_unix_ms
     end
 
-    def read(unprefixed_key : String) : Int64 | Nil
+    def read(unprefixed_key : String) : Int64?
       if exists?(unprefixed_key)
         @data[prefix_key(unprefixed_key)]["count"]
       end
diff --git a/src/defense/redis_store.cr b/src/defense/redis_store.cr
index 3dbd81e..cdb2444 100644
--- a/src/defense/redis_store.cr
+++ b/src/defense/redis_store.cr
@@ -18,9 +18,9 @@ module Defense
     def increment(unprefixed_key : String, expires_in : Int32) : Int64
       key = prefix_key(unprefixed_key)
 
-      @redis.multi do |r|
-        r.incr(key)
-        r.expire(key, expires_in)
+      @redis.multi do |red|
+        red.incr(key)
+        red.expire(key, expires_in)
       end.as(Array).first.as(Int64)
     end
 
@@ -28,7 +28,7 @@ module Defense
       @redis.exists(prefix_key(unprefixed_key)) == 1
     end
 
-    def read(unprefixed_key : String) : Int64 | Nil
+    def read(unprefixed_key : String) : Int64?
       @redis.get(prefix_key(unprefixed_key)).try(&.to_i64)
     end
 
diff --git a/src/defense/store.cr b/src/defense/store.cr
index 9a46b66..bfbd345 100644
--- a/src/defense/store.cr
+++ b/src/defense/store.cr
@@ -2,7 +2,7 @@ module Defense
   abstract class Store
     abstract def exists?(unprefixed_key : String) : Bool
     abstract def increment(unprefixed_key : String, expires_in : Int32) : Int64
-    abstract def read(unprefixed_key : String) : Int64 | Nil
+    abstract def read(unprefixed_key : String) : Int64?
     abstract def reset
 
     def prefix