diff --git a/docs/sphinx/source/whatsnew/v0.5.2.rst b/docs/sphinx/source/whatsnew/v0.5.2.rst
index 2c2c1db315..b325b9b101 100644
--- a/docs/sphinx/source/whatsnew/v0.5.2.rst
+++ b/docs/sphinx/source/whatsnew/v0.5.2.rst
@@ -24,6 +24,7 @@ Documentation
 Testing
 ~~~~~~~
 * Test Python 3.6 on Windows with Appveyor instead of 3.4. (:issue:`392`)
+* Fix failing test on pandas 0.22 (:issue:`406`)
 
 Contributors
 ~~~~~~~~~~~~
diff --git a/pvlib/test/conftest.py b/pvlib/test/conftest.py
index d85606826e..a706b9ab8c 100644
--- a/pvlib/test/conftest.py
+++ b/pvlib/test/conftest.py
@@ -42,6 +42,10 @@ def numpy_1_10():
     not numpy_1_10(), reason='requires numpy 1.10 or greater')
 
 
+def pandas_0_22():
+    return parse_version(pd.__version__) >= parse_version('0.22.0')
+
+
 def has_spa_c():
     try:
         from pvlib.spa_c_files.spa_py import spa_calc
diff --git a/pvlib/test/test_irradiance.py b/pvlib/test/test_irradiance.py
index 5af9e39b86..ef9599e7b2 100755
--- a/pvlib/test/test_irradiance.py
+++ b/pvlib/test/test_irradiance.py
@@ -15,7 +15,8 @@
 from pvlib import irradiance
 from pvlib import atmosphere
 
-from conftest import requires_ephem, requires_numba, needs_numpy_1_10
+from conftest import (requires_ephem, requires_numba, needs_numpy_1_10,
+                      pandas_0_22)
 
 # setup times and location to be tested.
 tus = Location(32.2, -111, 'US/Arizona', 700)
@@ -176,11 +177,16 @@ def test_perez_components():
         columns=['isotropic', 'circumsolar', 'horizon'],
         index=times
     )
+    if pandas_0_22():
+        expected_for_sum = expected.copy()
+        expected_for_sum.iloc[2] = 0
+    else:
+        expected_for_sum = expected
     sum_components = df_components.sum(axis=1)
 
     assert_series_equal(out, expected, check_less_precise=2)
     assert_frame_equal(df_components, expected_components)
-    assert_series_equal(sum_components, expected, check_less_precise=2)
+    assert_series_equal(sum_components, expected_for_sum, check_less_precise=2)
 
 @needs_numpy_1_10
 def test_perez_arrays():