diff --git a/README.md b/README.md
index 3cddef8..5b07a58 100644
--- a/README.md
+++ b/README.md
@@ -35,7 +35,7 @@ class StSegment(BaseSegment):
 ```
 * Render the segment from its grammar.
 ```python
-from pyx12lib.common.interchange.grammar import StSegment
+from pyx12lib.common.envelope.grammar import StSegment
 from pyx12lib.core.renderer import SegmentRenderer
 
 
@@ -49,7 +49,7 @@ class StRenderer(SegmentRenderer):
 ```
 * Advanced definition for element value getters
 ```python
-from pyx12lib.common.interchange.grammar import StSegment
+from pyx12lib.common.envelope.grammar import StSegment
 from pyx12lib.core.renderer import SegmentRenderer
 
 
diff --git a/pyx12lib/common/interchange/__init__.py b/pyx12lib/common/envelope/__init__.py
similarity index 100%
rename from pyx12lib/common/interchange/__init__.py
rename to pyx12lib/common/envelope/__init__.py
diff --git a/pyx12lib/common/interchange/grammar/__init__.py b/pyx12lib/common/envelope/grammar/__init__.py
similarity index 100%
rename from pyx12lib/common/interchange/grammar/__init__.py
rename to pyx12lib/common/envelope/grammar/__init__.py
diff --git a/pyx12lib/common/interchange/grammar/functional_group.py b/pyx12lib/common/envelope/grammar/functional_group.py
similarity index 100%
rename from pyx12lib/common/interchange/grammar/functional_group.py
rename to pyx12lib/common/envelope/grammar/functional_group.py
diff --git a/pyx12lib/common/interchange/grammar/interchange.py b/pyx12lib/common/envelope/grammar/interchange.py
similarity index 100%
rename from pyx12lib/common/interchange/grammar/interchange.py
rename to pyx12lib/common/envelope/grammar/interchange.py
diff --git a/pyx12lib/common/interchange/grammar/transaction_set.py b/pyx12lib/common/envelope/grammar/transaction_set.py
similarity index 100%
rename from pyx12lib/common/interchange/grammar/transaction_set.py
rename to pyx12lib/common/envelope/grammar/transaction_set.py
diff --git a/requirements.txt b/requirements.txt
index 4d23dd7..0b0a8ce 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -1,2 +1 @@
-python-dateutil>=2.6.1
 six>=1.11.0
diff --git a/setup.py b/setup.py
index aecf962..93c5783 100644
--- a/setup.py
+++ b/setup.py
@@ -13,7 +13,6 @@
     package_dir={"pyx12lib": "pyx12lib"},
     packages=setuptools.find_packages(),
     install_requires=[
-        "python-dateutil",
         "six",
     ],
     python_requires=">=3.6",
diff --git a/pyx12lib/core/tests/__init__.py b/tests/__init__.py
similarity index 100%
rename from pyx12lib/core/tests/__init__.py
rename to tests/__init__.py
diff --git a/pyx12lib/core/tests/test_composite_segment_renderer.py b/tests/test_composite_segment_renderer.py
similarity index 100%
rename from pyx12lib/core/tests/test_composite_segment_renderer.py
rename to tests/test_composite_segment_renderer.py
diff --git a/pyx12lib/core/tests/test_segment_renderer.py b/tests/test_segment_renderer.py
similarity index 100%
rename from pyx12lib/core/tests/test_segment_renderer.py
rename to tests/test_segment_renderer.py
diff --git a/pyx12lib/core/tests/test_segment_renderer_loop.py b/tests/test_segment_renderer_loop.py
similarity index 100%
rename from pyx12lib/core/tests/test_segment_renderer_loop.py
rename to tests/test_segment_renderer_loop.py