diff --git a/mrblib/array.rb b/mrblib/array.rb
index ae0868410..53d880660 100644
--- a/mrblib/array.rb
+++ b/mrblib/array.rb
@@ -84,8 +84,15 @@ class Array
   end
 
   def _inspect
-    return "[]" if self.size == 0
-    "["+self.map{|x|x.inspect}.join(", ")+"]"
+    size = self.size
+    return "[]" if size == 0
+    ary=[]
+    i=0
+    while i<size
+      ary<<self[i].inspect
+      i+=1
+    end
+    "["+ary.join(", ")+"]"
   end
   ##
   # Return the contents of this array as a string.
diff --git a/mrblib/hash.rb b/mrblib/hash.rb
index 582cfbc6c..6b61218ff 100644
--- a/mrblib/hash.rb
+++ b/mrblib/hash.rb
@@ -194,9 +194,16 @@ class Hash
   # internal method for Hash inspection
   def _inspect
     return "{}" if self.size == 0
-    "{"+self.map {|k,v|
-      k._inspect + "=>" + v._inspect
-    }.join(", ")+"}"
+    ary=[]
+    keys=self.keys
+    size=keys.size
+    i=0
+    while i<size
+      k=keys[i]
+      ary<<(k._inspect + "=>" + self[k]._inspect)
+      i+=1
+    end
+    "{"+ary.join(", ")+"}"
   end
   ##
   # Return the contents of this hash as a string.