diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 1ab5e78..81bf8c2 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -9,8 +9,8 @@ jobs:
   test:
     strategy:
       matrix:
-        os: ['ubuntu-20.04', 'macOS-11', 'windows-2019']
-        go: ['1.17.x', '1.16.x']
+        os: ['ubuntu-22.04', 'macOS-12', 'windows-2022']
+        go: ['1.19.x', '1.18.x']
     runs-on: ${{ matrix.os }}
     steps:
     - uses: actions/checkout@v3
diff --git a/go.mod b/go.mod
index 55266fc..a9a7869 100644
--- a/go.mod
+++ b/go.mod
@@ -1,6 +1,6 @@
 module github.com/mackerelio/mackerel-client-go
 
-go 1.14
+go 1.18
 
 require (
 	github.com/kylelemons/godebug v1.1.0
diff --git a/monitors.go b/monitors.go
index a61ca4d..f598df9 100644
--- a/monitors.go
+++ b/monitors.go
@@ -121,7 +121,6 @@ var (
 
 // Ensure only monitor types defined in this package can be assigned to the
 // Monitor interface.
-//
 func (m *MonitorConnectivity) isMonitor()     {}
 func (m *MonitorHostMetric) isMonitor()       {}
 func (m *MonitorServiceMetric) isMonitor()    {}