diff --git a/src/cligen/app.cr b/src/cligen/app.cr
index 554b753..19fec0f 100644
--- a/src/cligen/app.cr
+++ b/src/cligen/app.cr
@@ -18,9 +18,9 @@ module CliGen
       super
     end
 
-    def self.handle_command_raises(&block) : Nil
+    def self.handle_command_raises(&) : Nil
       begin
-        block.call
+        yield
       rescue e : CliGen::RuntimeError
         abort e.message
       rescue e : CliGen::ConfigurationError 
diff --git a/src/cligen/command_node.cr b/src/cligen/command_node.cr
index d752dcc..5cfb0a6 100644
--- a/src/cligen/command_node.cr
+++ b/src/cligen/command_node.cr
@@ -75,9 +75,9 @@ module CliGen
       @flags.find{|f| f.short == short}
     end
 
-    def handle_flag_raises(&work) 
+    def handle_flag_raises(&) : Nil
       begin 
-        work.call
+        yield
       rescue e : CliGen::RuntimeError
         abort e.message
       end