diff --git a/disk_test.go b/disk_test.go
index 0f2003020ac98709e763cb599b31452e6f9c8940..7f85a485f71a7dd2e6b77e895e09609320950308 100644
--- a/disk_test.go
+++ b/disk_test.go
@@ -58,7 +58,7 @@ func TestDiskUsageStat_String(t *testing.T) {
 		InodesFree:        6000,
 		InodesUsedPercent: 49.1,
 	}
-	e := `{"path":"/","total":1000,"free":2000,"used":3000,"usedPercent":50.1,"inodesTotal":4000,"inodesUsed":5000,"inodesFree":6000,"inodesUsedPercent":49.1}`
+	e := `{"path":"/","total":1000,"free":2000,"used":3000,"used_percent":50.1,"inodes_total":4000,"inodes_used":5000,"inodes_free":6000,"inodes_used_percent":49.1}`
 	if e != fmt.Sprintf("%v", v) {
 		t.Errorf("DiskUsageStat string is invalid: %v", v)
 	}
@@ -86,7 +86,7 @@ func TestDiskIOCountersStat_String(t *testing.T) {
 		WriteBytes:   400,
 		SerialNumber: "SERIAL",
 	}
-	e := `{"readCount":100,"writeCount":200,"readBytes":300,"writeBytes":400,"readTime":0,"writeTime":0,"name":"sd01","ioTime":0,"serialNumber":"SERIAL"}`
+	e := `{"read_count":100,"write_count":200,"read_bytes":300,"write_bytes":400,"read_time":0,"write_time":0,"name":"sd01","io_time":0,"serial_number":"SERIAL"}`
 	if e != fmt.Sprintf("%v", v) {
 		t.Errorf("DiskUsageStat string is invalid: %v", v)
 	}
diff --git a/host_test.go b/host_test.go
index 285ae138926a7a059f35f657c0c9f2b64083dea3..1d6852edd84cfcc7f8672b5e5e65506f2c3eec3d 100644
--- a/host_test.go
+++ b/host_test.go
@@ -47,7 +47,7 @@ func TestHostInfoStat_String(t *testing.T) {
 		OS:       "linux",
 		Platform: "ubuntu",
 	}
-	e := `{"hostname":"test","uptime":3000,"procs":100,"os":"linux","platform":"ubuntu","platformFamily":"","platformVersion":"","virtualizationSystem":"","virtualizationRole":""}`
+	e := `{"hostname":"test","uptime":3000,"procs":100,"os":"linux","platform":"ubuntu","platform_family":"","platform_version":"","virtualization_system":"","virtualization_role":""}`
 	if e != fmt.Sprintf("%v", v) {
 		t.Errorf("HostInfoStat string is invalid: %v", v)
 	}
diff --git a/mem_test.go b/mem_test.go
index 5631bdfe93b75a5103cbdc55c4c36ab9ba344d44..63421b30ebf8fc6f5834d839f005aa068c6638c2 100644
--- a/mem_test.go
+++ b/mem_test.go
@@ -35,7 +35,7 @@ func TestVirtualMemoryStat_String(t *testing.T) {
 		UsedPercent: 30.1,
 		Free:        40,
 	}
-	e := `{"total":10,"available":20,"used":30,"usedPercent":30.1,"free":40,"active":0,"inactive":0,"buffers":0,"cached":0,"wired":0,"shared":0}`
+	e := `{"total":10,"available":20,"used":30,"used_percent":30.1,"free":40,"active":0,"inactive":0,"buffers":0,"cached":0,"wired":0,"shared":0}`
 	if e != fmt.Sprintf("%v", v) {
 		t.Errorf("VirtualMemoryStat string is invalid: %v", v)
 	}
@@ -48,7 +48,7 @@ func TestSwapMemoryStat_String(t *testing.T) {
 		Free:        40,
 		UsedPercent: 30.1,
 	}
-	e := `{"total":10,"used":30,"free":40,"usedPercent":30.1,"sin":0,"sout":0}`
+	e := `{"total":10,"used":30,"free":40,"used_percent":30.1,"sin":0,"sout":0}`
 	if e != fmt.Sprintf("%v", v) {
 		t.Errorf("SwapMemoryStat string is invalid: %v", v)
 	}