diff --git a/python/lsst/ip/diffim/getTemplate.py b/python/lsst/ip/diffim/getTemplate.py
index 70382b038..d52e1e680 100644
--- a/python/lsst/ip/diffim/getTemplate.py
+++ b/python/lsst/ip/diffim/getTemplate.py
@@ -270,6 +270,37 @@ def getExposures(self, coaddExposureHandles, bbox, skymap, wcs):
 
         return pipeBase.Struct(coaddExposures=coaddExposures, dataIds=dataIds)
 
+    def checkPatch(self, coaddPatch, dataId):
+        """Check for invalid pixels in the coadd and raise warning if value is
+        non-zero.
+
+        Parameters
+        ----------
+        coaddPatch: `dict` [`int`, `list` [`lsst.afw.image.Exposure`]]
+            Coadd to be mosaicked, indexed on tract id.
+        dataId: `dict` [`int`, `list` [`lsst.daf.butler.DataCoordinate`]]
+            Record of the tract and patch of coaddPatch, indexed on
+            tract id.
+
+        Raises
+        ------
+        Warning
+            If invalid pixels are found in the coadd.
+        """
+        bad = np.logical_not(np.isfinite(coaddPatch.image.array))
+        y, x = np.nonzero(bad)
+        badN = len(np.nonzero(bad)[0])
+        if badN > 0:
+            print(dataId)
+            self.log.warning(
+                "%s invalid pixels in coadd using input tract=%s, patch=%s",
+                badN,
+                dataId['tract'],
+                dataId['patch'],
+            )
+        # modify patch to set mask planes correctly & get rid of invalid pixels
+        return coaddPatch
+
     @timeMethod
     def run(self, *, coaddExposureHandles, bbox, wcs, dataIds, physical_filter):
         """Warp coadds from multiple tracts and patches to form a template to
@@ -473,7 +504,7 @@ def _makeExposureCatalog(self, exposureRefs, dataIds):
         """
         catalog = afwTable.ExposureCatalog(self.schema)
         catalog.reserve(len(exposureRefs))
-        exposures = (exposureRef.get() for exposureRef in exposureRefs)
+        exposures = (self.checkPatch(exposureRef.get()) for exposureRef in exposureRefs)
         images = {}
         totalBox = geom.Box2I()
 
diff --git a/tests/test_getTemplate.py b/tests/test_getTemplate.py
index 6e888392c..59deb7156 100644
--- a/tests/test_getTemplate.py
+++ b/tests/test_getTemplate.py
@@ -22,7 +22,7 @@
 import collections
 import itertools
 import unittest
-
+from unittest.mock import patch
 import numpy as np
 
 import lsst.afw.geom
@@ -335,6 +335,51 @@ def testNanInputs(self, box=None, nInput=None):
         # in the template are closer to the original anymore.
         self.assertTrue(np.isfinite(result.template.image.array).all())
 
+    @patch('lsst.log.WARNING')
+    def testCheckPatchGoodPixels(self, mock_warning):
+        """ Check that coadd with no nan pixels and doesn't raise invalid pixel
+        warning.
+        """
+        getTemplate = lsst.ip.diffim.getTemplate.GetTemplateTask()
+        coaddPatch = self.exposure
+        dataId = self.dataIds[0]
+        getTemplate.checkPatch(coaddPatch, dataId)
+        self.assertEqual(mock_warning.call_count, 0)
+
+    @patch('lsst.log.WARNING')
+    def testCheckPatchOneBadPixel(self, mock_warning):
+        """ Check that coadd with one bad pixel raises one warning.
+        """
+        getTemplate = lsst.ip.diffim.getTemplate.GetTemplateTask()
+        coaddPatch = self.exposure
+        coaddPatch[0, 0] = (np.nan, 32, 4.0)
+        dataId = self.dataIds[0]
+        getTemplate.checkPatch(coaddPatch, dataId)
+        self.assertEqual(mock_warning.call_count, 1)
+
+    @patch('lsst.log.WARNING')
+    def testCheckPatchBadPixels(self, mock_warning):
+        """ Check that coadd with multiple bad pixels raises a single warning.
+        """
+        self.assertEqual(mock_warning.call_count, 1)
+
+    @patch('lsst.log.WARNING')
+    def testRunTemplateBadPixels(self):
+        """Test a bounding box that fully fits inside one tract, with only
+            that tract passed as input. This checks that the code handles a single
+            tract input correctly.
+        """
+        box = lsst.geom.Box2I(lsst.geom.Point2I(0, 0), lsst.geom.Point2I(180, 180))
+        task = lsst.ip.diffim.GetTemplateTask()
+        # Restrict to tract 0, since the box fits in just that tract.
+        # Task modifies the input bbox, so pass a copy.
+        result = task.run({0: self.patches[0]}, lsst.geom.Box2I(box),
+                          self.exposure.wcs, {0: self.dataIds[0]}, "a_test")
+
+        # All 4 patches from tract 0 are included in this template.
+        self._checkMetadata(result.template, task.config, box, self.exposure.wcs, 4)
+        self._checkPixels(result.template, task.config, box)
+
 
 def setup_module(module):
     lsst.utils.tests.init()