diff --git a/lib/matplotlib/cbook.py b/lib/matplotlib/cbook.py
index d0978fa46d92..1ff1191be3de 100644
--- a/lib/matplotlib/cbook.py
+++ b/lib/matplotlib/cbook.py
@@ -1734,10 +1734,10 @@ def get_siblings(self, a):
 
 
 def simple_linear_interpolation(a, steps):
+    steps = int(np.floor(steps))
     if steps == 1:
         return a
 
-    steps = np.floor(steps)
     new_length = ((len(a) - 1) * steps) + 1
     new_shape = list(a.shape)
     new_shape[0] = new_length
@@ -1747,7 +1747,6 @@ def simple_linear_interpolation(a, steps):
     a0 = a[0:-1]
     a1 = a[1:]
     delta = ((a1 - a0) / steps)
-    steps = int(steps)
     for i in range(1, steps):
         result[i::steps] = delta * i + a0
     result[steps::steps] = a1
diff --git a/lib/matplotlib/contour.py b/lib/matplotlib/contour.py
index 383978cbc44d..ff3514bf5cd9 100644
--- a/lib/matplotlib/contour.py
+++ b/lib/matplotlib/contour.py
@@ -474,20 +474,20 @@ def calc_label_rot_and_inline(self, slc, ind, lw, lc=None, spacing=5):
                 xy2 = mlab.less_simple_linear_interpolation(
                     pl, lc, [xi[1]])
 
-            # Make integer
+            # Make floating point representations of integers, keeping nans.
             I = [np.floor(I[0]), np.ceil(I[1])]
 
             # Actually break contours
             if closed:
                 # This will remove contour if shorter than label
                 if np.all(~np.isnan(I)):
-                    nlc.append(np.r_[xy2, lc[I[1]:I[0] + 1], xy1])
+                    nlc.append(np.r_[xy2, lc[int(I[1]):int(I[0]) + 1], xy1])
             else:
                 # These will remove pieces of contour if they have length zero
                 if not np.isnan(I[0]):
-                    nlc.append(np.r_[lc[:I[0] + 1], xy1])
+                    nlc.append(np.r_[lc[:int(I[0]) + 1], xy1])
                 if not np.isnan(I[1]):
-                    nlc.append(np.r_[xy2, lc[I[1]:]])
+                    nlc.append(np.r_[xy2, lc[int(I[1]):]])
 
             # The current implementation removes contours completely
             # covered by labels.  Uncomment line below to keep
diff --git a/lib/matplotlib/tests/test_axes.py b/lib/matplotlib/tests/test_axes.py
index 638e4907095a..6f89ac1d1349 100644
--- a/lib/matplotlib/tests/test_axes.py
+++ b/lib/matplotlib/tests/test_axes.py
@@ -523,7 +523,7 @@ def test_nonfinite_limits():
         y = np.log(x)
     finally:
         np.seterr(**olderr)
-    x[len(x)/2] = np.nan
+    x[len(x) // 2] = np.nan
     fig = plt.figure()
     ax = fig.add_subplot(111)
     ax.plot(x, y)
diff --git a/lib/matplotlib/tests/test_mlab.py b/lib/matplotlib/tests/test_mlab.py
index 0cc991f05ebf..3dbf0dd54977 100644
--- a/lib/matplotlib/tests/test_mlab.py
+++ b/lib/matplotlib/tests/test_mlab.py
@@ -1325,8 +1325,8 @@ def createStim(self, fstims, iscomplex, sides, nsides, len_x=None,
 
         freqs_specgram = freqs_density
         # time points for specgram
-        t_start = NFFT_specgram_real/2
-        t_stop = len(x) - NFFT_specgram_real/2+1
+        t_start = NFFT_specgram_real // 2
+        t_stop = len(x) - NFFT_specgram_real // 2 + 1
         t_step = NFFT_specgram_real - nover_specgram_real
         t_specgram = x[t_start:t_stop:t_step]
         if NFFT_specgram_real % 2:
diff --git a/lib/matplotlib/tests/test_simplification.py b/lib/matplotlib/tests/test_simplification.py
index a1bc217bf6fd..e99ac097a989 100644
--- a/lib/matplotlib/tests/test_simplification.py
+++ b/lib/matplotlib/tests/test_simplification.py
@@ -153,7 +153,7 @@ def test_start_with_moveto():
         decodebytes = base64.decodestring
 
     verts = np.fromstring(decodebytes(data), dtype='<i4')
-    verts = verts.reshape((len(verts) / 2, 2))
+    verts = verts.reshape((len(verts) // 2, 2))
     path = Path(verts)
     segs = path.iter_segments(transforms.IdentityTransform(), clip=(0.0, 0.0, 100.0, 100.0))
     segs = list(segs)
diff --git a/lib/matplotlib/tri/trirefine.py b/lib/matplotlib/tri/trirefine.py
index ae2f257a1f5e..11e3fff3e468 100644
--- a/lib/matplotlib/tri/trirefine.py
+++ b/lib/matplotlib/tri/trirefine.py
@@ -231,7 +231,7 @@ def _refine_triangulation_once(triangulation, ancestors=None):
         # points
         # hint: each apex is shared by 2 masked_triangles except the borders.
         borders = np.sum(neighbors == -1)
-        added_pts = (3*ntri + borders) / 2
+        added_pts = (3*ntri + borders) // 2
         refi_npts = npts + added_pts
         refi_x = np.zeros(refi_npts)
         refi_y = np.zeros(refi_npts)