diff --git a/beat/core/test/test_format_composed.py b/beat/core/test/test_format_composed.py
index 58f30719e46b7317dfcefcfde672b1d0b2ff056f..31f9aadab95d7822a979fa1a0d118212adf0e23c 100644
--- a/beat/core/test/test_format_composed.py
+++ b/beat/core/test/test_format_composed.py
@@ -34,8 +34,6 @@
 ###################################################################################
 
 
-import os
-
 import numpy
 import nose.tools
 
@@ -47,16 +45,16 @@ from . import prefix
 def test_valid():
 
     df = DataFormat(prefix, "user/composed/1")
-    assert df.valid
+    nose.tools.assert_true(df.valid)
 
     ftype = df.type
 
-    assert numpy.issubdtype(ftype.integers.value8, numpy.int8)
-    assert numpy.issubdtype(ftype.integers.value16, numpy.int16)
-    assert numpy.issubdtype(ftype.integers.value32, numpy.int32)
-    assert numpy.issubdtype(ftype.integers.value64, numpy.int64)
-    assert numpy.issubdtype(ftype.floats.value32, numpy.float32)
-    assert numpy.issubdtype(ftype.floats.value64, numpy.float64)
+    nose.tools.assert_true(numpy.issubdtype(ftype.integers.value8, numpy.int8))
+    nose.tools.assert_true(numpy.issubdtype(ftype.integers.value16, numpy.int16))
+    nose.tools.assert_true(numpy.issubdtype(ftype.integers.value32, numpy.int32))
+    nose.tools.assert_true(numpy.issubdtype(ftype.integers.value64, numpy.int64))
+    nose.tools.assert_true(numpy.issubdtype(ftype.floats.value32, numpy.float32))
+    nose.tools.assert_true(numpy.issubdtype(ftype.floats.value64, numpy.float64))
 
     obj = ftype(
         integers=dict(
@@ -81,31 +79,31 @@ def test_valid():
     nose.tools.eq_(obj.integers.value64, 2 ** 62)
 
     nose.tools.eq_(obj.floats.value32.dtype, numpy.float32)
-    assert numpy.isclose(obj.floats.value32, 3.14)
+    nose.tools.assert_true(numpy.isclose(obj.floats.value32, 3.14))
 
     nose.tools.eq_(obj.floats.value64.dtype, numpy.float64)
-    assert numpy.isclose(obj.floats.value64, 2.78)
+    nose.tools.assert_true(numpy.isclose(obj.floats.value64, 2.78))
 
     # checks JSON enconding
     copy = ftype()
     copy.from_dict(obj.as_dict())
-    assert copy.isclose(obj), "%r is not close enough to %r" % (
-        copy.as_dict(),
-        obj.as_dict(),
+    nose.tools.assert_true(
+        copy.isclose(obj),
+        "%r is not close enough to %r" % (copy.as_dict(), obj.as_dict()),
     )
 
     # checks binary encoding
     copy = ftype()
     copy.unpack(obj.pack())
-    assert copy.isclose(obj), "%r is not close enough to %r" % (
-        copy.as_dict(),
-        obj.as_dict(),
+    nose.tools.assert_true(
+        copy.isclose(obj),
+        "%r is not close enough to %r" % (copy.as_dict(), obj.as_dict()),
     )
 
 
 def test_invalid():
 
     df = DataFormat(prefix, "user/composed_unknown/1")
-    assert df.valid is False
-    assert df.errors[0].find("referred dataformat") != -1
-    assert df.errors[0].find("invalid") != -1
+    nose.tools.assert_false(df.valid)
+    nose.tools.assert_not_equal(df.errors[0].find("referred dataformat"), -1)
+    nose.tools.assert_not_equal(df.errors[0].find("invalid"), -1)