diff --git a/mrblib/array.rb b/mrblib/array.rb
index cbeaa6783..a7c0f84cc 100644
--- a/mrblib/array.rb
+++ b/mrblib/array.rb
@@ -17,7 +17,7 @@ class Array
 
     idx = 0
     while idx < length
-      block.call(self[idx])
+      yield self[idx]
       idx += 1
     end
     self
@@ -37,7 +37,7 @@ class Array
 
     idx = 0
     while idx < length
-      block.call(idx)
+      yield idx
       idx += 1
     end
     self
diff --git a/mrblib/numeric.rb b/mrblib/numeric.rb
index 322afd409..b25513ef4 100644
--- a/mrblib/numeric.rb
+++ b/mrblib/numeric.rb
@@ -49,7 +49,7 @@ class Integer
 
     i = self.to_i
     while i >= num
-      block.call(i)
+      yield i
       i -= 1
     end
     self
@@ -74,7 +74,7 @@ class Integer
 
     i = 0
     while i < self
-      block.call(i)
+      yield i
       i += 1
     end
     self
@@ -90,7 +90,7 @@ class Integer
 
     i = self.to_i
     while i <= num
-      block.call(i)
+      yield i
       i += 1
     end
     self