diff --git a/ext/cvmat.cpp b/ext/cvmat.cpp
index 205f38f..6a6a475 100644
--- a/ext/cvmat.cpp
+++ b/ext/cvmat.cpp
@@ -245,17 +245,17 @@ void define_ruby_class()
   rb_define_method(rb_klass, "not", RUBY_METHOD_FUNC(rb_not), 0);
   rb_define_method(rb_klass, "not!", RUBY_METHOD_FUNC(rb_not_bang), 0);
   rb_define_method(rb_klass, "eq", RUBY_METHOD_FUNC(rb_eq), 1);
-  rb_define_alias(rb_klass, "==", "eq");
+  // rb_define_alias(rb_klass, "==", "eq");
   rb_define_method(rb_klass, "gt", RUBY_METHOD_FUNC(rb_gt), 1);
-  rb_define_alias(rb_klass, ">", "gt");
+  // rb_define_alias(rb_klass, ">", "gt");
   rb_define_method(rb_klass, "ge", RUBY_METHOD_FUNC(rb_ge), 1);
-  rb_define_alias(rb_klass, ">=", "ge");
+  // rb_define_alias(rb_klass, ">=", "ge");
   rb_define_method(rb_klass, "lt", RUBY_METHOD_FUNC(rb_lt), 1);
-  rb_define_alias(rb_klass, "<", "lt");
+  // rb_define_alias(rb_klass, "<", "lt");
   rb_define_method(rb_klass, "le", RUBY_METHOD_FUNC(rb_le), 1);
-  rb_define_alias(rb_klass, "<=", "le");
+  // rb_define_alias(rb_klass, "<=", "le");
   rb_define_method(rb_klass, "ne", RUBY_METHOD_FUNC(rb_ne), 1);
-  rb_define_alias(rb_klass, "!=", "ne");
+  // rb_define_alias(rb_klass, "!=", "ne");
   rb_define_method(rb_klass, "in_range", RUBY_METHOD_FUNC(rb_in_range), 2);
   rb_define_method(rb_klass, "abs_diff", RUBY_METHOD_FUNC(rb_abs_diff), 1);
   rb_define_method(rb_klass, "count_non_zero", RUBY_METHOD_FUNC(rb_count_non_zero), 0);
diff --git a/test/helper.rb b/test/helper.rb
index 5d0de83..7fef4d8 100755
--- a/test/helper.rb
+++ b/test/helper.rb
@@ -6,6 +6,36 @@ require 'opencv'
 include OpenCV
 
 class OpenCVTestCase < Test::Unit::TestCase
+  CvMat.class_eval do
+    # Range check for debug
+    alias original_aref []
+    alias original_aset []=;
+    
+    def [](*idx)
+      if idx.size == 1
+        n = idx[0]
+        throw ArgumentError.new("index #{n} is out of range") if n >= rows * cols
+      else
+        j, i = *idx
+        throw ArgumentError.new("index for row #{j} is out of range") if j >= rows
+        throw ArgumentError.new("index for column #{i} is out of range") if i >= cols
+      end
+      original_aref(*idx)
+    end
+
+    def []=(*idx, val)
+      if idx.size == 1
+        n = idx[0]
+        throw ArgumentError.new("index #{n} is out of range") if n >= rows * cols
+      else
+        j, i = *idx
+        throw ArgumentError.new("index for row #{j} is out of range") if j >= rows
+        throw ArgumentError.new("index for column #{i} is out of range") if i >= cols
+      end
+      original_aset(*idx, val)
+    end
+  end
+
   def get_sample(filename, iscolor = nil)
     IplImage::load('samples/' + filename, iscolor)
   end
diff --git a/test/test_cvmat.rb b/test/test_cvmat.rb
index 51c1975..9064428 100755
--- a/test/test_cvmat.rb
+++ b/test/test_cvmat.rb
@@ -1324,7 +1324,80 @@ class TestCvMat < OpenCVTestCase
       CvScalar.new(n, 0, 0, 0)
     }
   end
-  
+
+  def test_gt
+    m0 = create_cvmat(6, 4, :cv8u, 1) { |j, i, c|
+      CvScalar.new(c, 0, 0, 0)
+    }
+    m1 = m0.gt(10)
+
+    assert_equal(m0.height, m1.height)
+    assert_equal(m0.width, m1.width)
+    assert_each_cvscalar(m) { |j, i, c|
+      n = (c > 10) ? 0xff : 0
+      CvScalar.new(n, 0, 0, 0)
+    }
+
+  end
+
+  def test_ge
+    m0 = create_cvmat(6, 4, :cv8u, 1) { |j, i, c|
+      CvScalar.new(c, 0, 0, 0)
+    }
+    m1 = m0.ge(10)
+
+    assert_equal(m0.height, m1.height)
+    assert_equal(m0.width, m1.width)
+    assert_each_cvscalar(m) { |j, i, c|
+      n = (c >= 10) ? 0xff : 0
+      CvScalar.new(n, 0, 0, 0)
+    }
+  end
+
+  def test_lt
+    m0 = create_cvmat(6, 4, :cv8u, 1) { |j, i, c|
+      CvScalar.new(c, 0, 0, 0)
+    }
+    m1 = m0.lt(10)
+    
+    assert_equal(m0.height, m1.height)
+    assert_equal(m0.width, m1.width)
+    assert_each_cvscalar(m1) { |j, i, c|
+      n = (c < 10) ? 0xff : 0
+      CvScalar.new(n, 0, 0, 0)
+    }
+  end
+
+  def test_le
+    m0 = create_cvmat(6, 4, :cv8u, 1) { |j, i, c|
+      CvScalar.new(c, 0, 0, 0)
+    }
+    m1 = m0.le(10)
+    
+    assert_equal(m0.height, m1.height)
+    assert_equal(m0.width, m1.width)
+    assert_each_cvscalar(m1) { |j, i, c|
+      n = (c <= 10) ? 0xff : 0
+      CvScalar.new(n, 0, 0, 0)
+    }
+  end
+
+  def test_ne
+    m0 = create_cvmat(6, 4, :cv8u, 1) { |j, i, c|
+      CvScalar.new(c, 0, 0, 0)
+    }
+    m1 = m0.ne(10)
+    
+    assert_equal(m0.height, m1.height)
+    assert_equal(m0.width, m1.width)
+    assert_each_cvscalar(m1) { |j, i, c|
+      n = (c != 10) ? 0xff : 0
+      CvScalar.new(n, 0, 0, 0)
+    }
+  end
+
+
+
   # def test_avg_sdv
   #   m = CvMat.new(1, 8, CV_32F)
   #   [2, 4, 4, 4, 5, 5, 7, 9].each_with_index { |v, i|