diff --git a/daemon/client/checks/common.go b/daemon/client/checks/common.go
index 79b47c9..74e7c07 100644
--- a/daemon/client/checks/common.go
+++ b/daemon/client/checks/common.go
@@ -22,6 +22,7 @@ const (
 	kubernetesIP = "172.30.0.1"
 )
 
+var num = regexp.MustCompile(`\d+(?:\.\d+)?`)
 
 func CheckExternalSystem(url string) (error) {
 	if err := checkHttp(url); err != nil {
@@ -94,12 +95,19 @@ func getEndpoint(slow bool) string {
 	}
 }
 
+// isVgSizeOk returns true if vgs output in stdOut indicates that the volume
+// group free space is equal or above the percentage treshold okSize, which is
+// expected to be in the range [0, 100].
 func isVgSizeOk(stdOut string, okSize int) bool {
 	// Example
 	// 5.37 26.84 vg_fast_registry
 	// 5.37 26.84 vg_slow
-	num := regexp.MustCompile("(\\d+\\.\\d+)")
-	nums := num.FindAllString(stdOut, -1)
+	nums := num.FindAllString(stdOut, 2)
+
+	if len(nums) != 2 {
+		log.Println("Unable to parse vgs output:", stdOut)
+		return false
+	}
 
 	free, err := strconv.ParseFloat(nums[0], 64)
 	if (err != nil) {
@@ -114,7 +122,7 @@ func isVgSizeOk(stdOut string, okSize int) bool {
 
 	// calculate usage
 	if (100 / size * free < float64(okSize)) {
-		msg := fmt.Sprintf("VG free size is below treshold. Size: %v, free: %v, treshold: %v %", size, free, okSize)
+		msg := fmt.Sprintf("VG free size is below treshold. Size: %v, free: %v, treshold: %v %%", size, free, okSize)
 		log.Println(msg)
 		return false
 	}
@@ -122,12 +130,13 @@ func isVgSizeOk(stdOut string, okSize int) bool {
 	return true
 }
 
+// isLvsSizeOk returns true if lvs output in stdOut indicates that the logical
+// volume percentage full for data and metadata are both below the threshold
+// okSize, which is expected to be in the range [0, 100].
 func isLvsSizeOk(stdOut string, okSize int) bool {
 	// Examples
 	// 42.10  8.86   docker-pool
 	// 13.63  8.93   lv_fast_registry_pool
-	num := regexp.MustCompile("(\\d+\\.\\d+)")
-
 	checksOk := 0
 	for _, nr := range num.FindAllString(stdOut, -1) {
 		i, err := strconv.ParseFloat(nr, 64)
diff --git a/daemon/client/checks/common_test.go b/daemon/client/checks/common_test.go
new file mode 100644
index 0000000..52c559e
--- /dev/null
+++ b/daemon/client/checks/common_test.go
@@ -0,0 +1,32 @@
+package checks
+
+import (
+	"io/ioutil"
+	"log"
+	"testing"
+)
+
+func init() {
+	// Omit standard log output when running tests to allow one to focus on
+	// actual test results.
+	log.SetOutput(ioutil.Discard)
+}
+
+func TestIsVgSizeOk(t *testing.T) {
+	tests := []struct {
+		line   string
+		okSize int
+		want   bool
+	}{
+		{"invalid input", 99, false},
+		{"5.37 26.84 vg_slow", 5, true},
+		{"5.37 26.84 vg_slow", 25, false},
+		{"      0 511.03 fedora", 10, false},
+		{"\t25\t250 test", 10, true},
+	}
+	for _, tt := range tests {
+		if got := isVgSizeOk(tt.line, tt.okSize); got != tt.want {
+			t.Errorf("isVgSizeOk(%q, %v) = %v, want %v", tt.line, tt.okSize, got, tt.want)
+		}
+	}
+}