diff --git a/deltasigma/_utils.py b/deltasigma/_utils.py
index 097f803..679be82 100644
--- a/deltasigma/_utils.py
+++ b/deltasigma/_utils.py
@@ -91,7 +91,7 @@ def carray(x):
     """Check that x is an ndarray. If not, try to convert it to ndarray.
     """
     if not isinstance(x, np.ndarray):
-        if not isinstance(x, collections.Iterable):
+        if not isinstance(x, collections.abc.Iterable):
             x = np.array((x,))
         else:
             x = np.array(x)
@@ -448,7 +448,7 @@ def _get_zpk(arg, input=0):
         z, p, k = sys.zeros, sys.poles, sys.gain
     elif _is_A_B_C_D(arg):
         z, p, k = ss2zpk(*arg, input=input)
-    elif isinstance(arg, collections.Iterable):
+    elif isinstance(arg, collections.abc.Iterable):
         ri = 0
         for i in arg:
             # Note we do not check if the user has assembled a list with
@@ -528,7 +528,7 @@ def _get_num_den(arg, input=0):
         num, den = zpk2tf(*arg)
     elif _is_A_B_C_D(arg):
         num, den = ss2tf(*arg, input=input)
-    elif isinstance(arg, collections.Iterable):
+    elif isinstance(arg, collections.abc.Iterable):
         ri = 0
         for i in arg:
             # Note we do not check if the user has assembled a list with
@@ -610,7 +610,7 @@ def _getABCD(arg):
     elif _is_zpk(arg) or _is_num_den(arg) or _is_A_B_C_D(arg):
         sys = lti(*arg).to_ss()
         A, B, C, D = sys.A, sys.B, sys.C, sys.D
-    elif isinstance(arg, collections.Iterable):
+    elif isinstance(arg, collections.abc.Iterable):
         A, B, C, D = None, None, None, None
         for i in arg:
             # Note we do not check if the user has assembled a list with
@@ -641,25 +641,25 @@ def _getABCD(arg):
 
 def _is_zpk(arg):
     """Can the argument be safely assumed to be a zpk tuple?"""
-    return isinstance(arg, collections.Iterable) and len(arg) == 3 and \
-        isinstance(arg[0], collections.Iterable) and \
-        isinstance(arg[1], collections.Iterable) and np.isscalar(arg[2])
+    return isinstance(arg, collections.abc.Iterable) and len(arg) == 3 and \
+        isinstance(arg[0], collections.abc.Iterable) and \
+        isinstance(arg[1], collections.abc.Iterable) and np.isscalar(arg[2])
 
 
 def _is_num_den(arg):
     """Can the argument be safely assumed to be a num, den tuple?"""
-    return isinstance(arg, collections.Iterable) and len(arg) == 2 and \
-        isinstance(arg[0], collections.Iterable) and \
-        isinstance(arg[1], collections.Iterable)
+    return isinstance(arg, collections.abc.Iterable) and len(arg) == 2 and \
+        isinstance(arg[0], collections.abc.Iterable) and \
+        isinstance(arg[1], collections.abc.Iterable)
 
 
 def _is_A_B_C_D(arg):
     """Can the argument be safely assumed to be an (A, B, C, D) tuple?"""
-    return isinstance(arg, collections.Iterable) and len(arg) == 4 and \
-        (isinstance(arg[0], collections.Iterable) or np.is_scalar(arg[0])) and \
-        (isinstance(arg[1], collections.Iterable) or np.is_scalar(arg[1])) and \
-        (isinstance(arg[2], collections.Iterable) or np.is_scalar(arg[2])) and \
-        (isinstance(arg[3], collections.Iterable) or np.is_scalar(arg[3]))
+    return isinstance(arg, collections.abc.Iterable) and len(arg) == 4 and \
+        (isinstance(arg[0], collections.abc.Iterable) or np.is_scalar(arg[0])) and \
+        (isinstance(arg[1], collections.abc.Iterable) or np.is_scalar(arg[1])) and \
+        (isinstance(arg[2], collections.abc.Iterable) or np.is_scalar(arg[2])) and \
+        (isinstance(arg[3], collections.abc.Iterable) or np.is_scalar(arg[3]))
 
 
 def mround(x):