diff --git a/ext/opencv/cvmat.cpp b/ext/opencv/cvmat.cpp
index dc174f9..fbc98c9 100644
--- a/ext/opencv/cvmat.cpp
+++ b/ext/opencv/cvmat.cpp
@@ -705,7 +705,7 @@ rb_clone(VALUE self)
 VALUE
 rb_copy(int argc, VALUE *argv, VALUE self)
 {
-  VALUE value, copied, tmp;
+  VALUE value, copied;
   CvMat *src = CVMAT(self);
   rb_scan_args(argc, argv, "01", &value);
   if (argc == 0) {
@@ -724,7 +724,7 @@ rb_copy(int argc, VALUE *argv, VALUE self)
       if (n > 0) {
         copied = rb_ary_new2(n);
         for (int i = 0; i < n; i++) {
-	  tmp = new_object(src->rows, src->cols, cvGetElemType(src));
+	  VALUE tmp = new_object(src->rows, src->cols, cvGetElemType(src));
 	  cvCopy(src, CVMAT(tmp));
           rb_ary_store(copied, i, tmp);
         }
@@ -733,8 +733,9 @@ rb_copy(int argc, VALUE *argv, VALUE self)
       else {
         return Qnil;
       }
-    }else
-      rb_raise(rb_eArgError, "");
+    }
+    else
+      rb_raise(rb_eArgError, "Argument should be CvMat or Fixnum");
   }
 }
 
diff --git a/test/test_cvmat.rb b/test/test_cvmat.rb
index 2621863..5e798be 100755
--- a/test/test_cvmat.rb
+++ b/test/test_cvmat.rb
@@ -199,19 +199,8 @@ class TestCvMat < OpenCVTestCase
     }
     assert_nil(m1.copy(-1))
 
-    flunk('FIXME: CvUnmatchedSizes and CvUnmatchedFormats are not implemented yet')
-    m2 = CvMat.new(1, 2, CV_32F, 1)
-    assert_raise(CvUnmatchedSizes) {
-      m1.copy(m2)
-    }
-
-    m2 = CvMat.new(10, 20, CV_32F, 3)
-    assert_raise(CvUnmatchedFormats) {
-      m1.copy(m2)
-    }
-    m2 = CvMat.new(10, 20, CV_8U, 1)
-    assert_raise(CvUnmatchedFormats) {
-      m1.copy(m2)
+    assert_raise(ArgumentError) {
+      m1.copy('foobar')
     }
   end