diff --git a/azure-pipelines.yml b/azure-pipelines.yml
index c096006af0b1051b7c45b7353719dbcb6903fc35..15053f74b138af929b0139c7921729acafb9721a 100644
--- a/azure-pipelines.yml
+++ b/azure-pipelines.yml
@@ -2,13 +2,15 @@ jobs:
 -
     job: 'Pytest'
     pool:
-        vmImage: 'ubuntu-16.04'
+        vmImage: 'ubuntu-latest'
     strategy:
         matrix:
             Python27:
                 python.version: '2.7'
             Python36:
                 python.version: '3.6'
+            Python37:
+                python.version: '3.7'
 
     steps:
     -
@@ -34,11 +36,11 @@ jobs:
 -
     job: 'Flake8'
     pool:
-        vmImage: 'ubuntu-16.04'
+        vmImage: 'ubuntu-latest'
     strategy:
         matrix:
-            Python36:
-                python.version: '3.6'
+            Python37:
+                python.version: '3.7'
 
     steps:
     -
@@ -57,11 +59,11 @@ jobs:
 -
     job: 'Pylint'
     pool:
-        vmImage: 'ubuntu-16.04'
+        vmImage: 'ubuntu-latest'
     strategy:
         matrix:
-            Python36:
-                python.version: '3.6'
+            Python37:
+                python.version: '3.7'
 
     steps:
     -
@@ -74,6 +76,6 @@ jobs:
             set -e
             EXTRA_INSTALL="pymbolic matplotlib"
             curl -L -O -k https://gitlab.tiker.net/inducer/ci-support/raw/master/prepare-and-run-pylint.sh
-            . ./prepare-and-run-pylint.sh pytools test/test_*.py
+            . ./prepare-and-run-pylint.sh islpy test/test_*.py
 
         displayName: 'Pylint'
diff --git a/pytools/prefork.py b/pytools/prefork.py
index be388f3d5ab60e8abc8b42898dc3ad9619ce624d..864c168a10b9e9a161ee64aa1aafbfc4591205ea 100644
--- a/pytools/prefork.py
+++ b/pytools/prefork.py
@@ -53,7 +53,7 @@ class DirectForker(object):
             if error_on_nonzero and popen.returncode:
                 raise ExecError("status %d invoking '%s': %s"
                                 % (popen.returncode, " ".join(cmdline),
-                                   stderr_data))
+                                   stderr_data.decode("utf-8", errors="replace")))
 
             return popen.returncode, stdout_data, stderr_data
         except OSError as e: