diff --git a/spec/support/cli.cr b/spec/support/cli.cr
index c9c3cae5..d7319d37 100644
--- a/spec/support/cli.cr
+++ b/spec/support/cli.cr
@@ -8,7 +8,7 @@ Spec.before_each do
   end
 end
 
-def with_shard(metadata, lock = nil, override = nil)
+def with_shard(metadata, lock = nil, override = nil, &)
   Dir.cd(application_path) do
     File.write "shard.yml", to_shard_yaml(metadata)
     File.write "shard.lock", to_lock_yaml(lock) if lock
diff --git a/src/commands/command.cr b/src/commands/command.cr
index 11f3ca90..cb84fd6a 100644
--- a/src/commands/command.cr
+++ b/src/commands/command.cr
@@ -73,7 +73,7 @@ module Shards
       Shards::Lock.write(packages, override_path, LOCK_FILENAME)
     end
 
-    def handle_resolver_errors
+    def handle_resolver_errors(&)
       yield
     rescue e : Molinillo::ResolverError
       Log.error { e.message }
diff --git a/src/ext/yaml.cr b/src/ext/yaml.cr
index e4fffed7..90cf1cb7 100644
--- a/src/ext/yaml.cr
+++ b/src/ext/yaml.cr
@@ -4,7 +4,7 @@ module YAML
   class PullParser
     # Iterates a sequence, yielding on each new entry until the sequence is
     # terminated.
-    def each_in_sequence : Nil
+    def each_in_sequence(&) : Nil
       read_sequence_start
       until kind == YAML::EventKind::SEQUENCE_END
         yield
@@ -14,7 +14,7 @@ module YAML
 
     # Iterates a mapping, yielding on each new entry until the mapping is
     # terminated.
-    def each_in_mapping : Nil
+    def each_in_mapping(&) : Nil
       read_mapping_start
       until kind == YAML::EventKind::MAPPING_END
         yield
diff --git a/src/resolvers/fossil.cr b/src/resolvers/fossil.cr
index b8724a85..b568994c 100644
--- a/src/resolvers/fossil.cr
+++ b/src/resolvers/fossil.cr
@@ -380,7 +380,7 @@ module Shards
       end
     end
 
-    private def fossil_retry(err = "Failed to fetch repository")
+    private def fossil_retry(err = "Failed to fetch repository", &)
       retries = 0
       loop do
         yield
diff --git a/src/resolvers/git.cr b/src/resolvers/git.cr
index b2c1c5fd..f150ca36 100644
--- a/src/resolvers/git.cr
+++ b/src/resolvers/git.cr
@@ -327,7 +327,7 @@ module Shards
       end
     end
 
-    private def git_retry(err = "Failed to fetch repository")
+    private def git_retry(err = "Failed to fetch repository", &)
       retries = 0
       loop do
         yield
diff --git a/src/resolvers/hg.cr b/src/resolvers/hg.cr
index 2d33a720..7568b09d 100644
--- a/src/resolvers/hg.cr
+++ b/src/resolvers/hg.cr
@@ -352,7 +352,7 @@ module Shards
       end
     end
 
-    private def hg_retry(err = "Failed to update repository")
+    private def hg_retry(err = "Failed to update repository", &)
       retries = 0
       loop do
         return yield
diff --git a/src/versions.cr b/src/versions.cr
index 1ee1562f..0795bbf9 100644
--- a/src/versions.cr
+++ b/src/versions.cr
@@ -63,7 +63,7 @@ module Shards
         end
       end
 
-      def only_zeroes?
+      def only_zeroes?(&)
         return if empty?
         yield unless to_i? == 0