diff --git a/pint/compat/__init__.py b/pint/compat/__init__.py
index eaf639ff1..bfe88e75f 100644
--- a/pint/compat/__init__.py
+++ b/pint/compat/__init__.py
@@ -122,6 +122,8 @@ def __array_function__(self, *args, **kwargs):
     if HAS_NUMPY_ARRAY_FUNCTION:
         warnings.warn(_msg, BehaviorChangeWarning)
 
+    NP_NO_VALUE = np._NoValue
+
 except ImportError:
 
     np = None
@@ -133,6 +135,7 @@ class ndarray(object):
     NUMPY_VER = '0'
     NUMERIC_TYPES = (Number, Decimal)
     HAS_NUMPY_ARRAY_FUNCTION = False
+    NP_NO_VALUE = None
 
     def _to_magnitude(value, force_ndarray=False):
         if isinstance(value, (dict, bool)) or value is None:
diff --git a/pint/numpy_func.py b/pint/numpy_func.py
index 538a0b462..7131bdde5 100644
--- a/pint/numpy_func.py
+++ b/pint/numpy_func.py
@@ -7,7 +7,7 @@
     :license: BSD, see LICENSE for more details.
 """
 
-from .compat import is_upcast_type, np, string_types, eq
+from .compat import NP_NO_VALUE, is_upcast_type, np, string_types, eq
 from .errors import DimensionalityError
 from .util import iterable, sized
 
@@ -140,6 +140,10 @@ def decorator(func):
 
 def implement_func(func_type, func_str, input_units=None, output_unit=None):
     """TODO"""
+    # If NumPy is not available, do not attempt implement that which does not exist
+    if np is None:
+        return
+
     func = getattr(np, func_str)
 
     @implements(func_str, func_type)
@@ -418,9 +422,9 @@ def _unwrap(p, discont=None, axis=-1):
 
 
 @implements('amin', 'function')
-def _amin(a, axis=None, out=None, keepdims=np._NoValue, initial=np._NoValue,
-          where=np._NoValue):
-    if initial == np._NoValue:
+def _amin(a, axis=None, out=None, keepdims=NP_NO_VALUE, initial=NP_NO_VALUE,
+          where=NP_NO_VALUE):
+    if initial == NP_NO_VALUE:
         (a,), output_wrap = unwrap_and_wrap_consistent_units(a)
     else:
         (a, initial), output_wrap = unwrap_and_wrap_consistent_units(a, initial)
@@ -429,9 +433,9 @@ def _amin(a, axis=None, out=None, keepdims=np._NoValue, initial=np._NoValue,
 
 
 @implements('amax', 'function')
-def _amax(a, axis=None, out=None, keepdims=np._NoValue, initial=np._NoValue,
-          where=np._NoValue):
-    if initial == np._NoValue:
+def _amax(a, axis=None, out=None, keepdims=NP_NO_VALUE, initial=NP_NO_VALUE,
+          where=NP_NO_VALUE):
+    if initial == NP_NO_VALUE:
         (a,), output_wrap = unwrap_and_wrap_consistent_units(a)
     else:
         (a, initial), output_wrap = unwrap_and_wrap_consistent_units(a, initial)