diff --git a/errors.go b/errors.go
index d300169..e5dd078 100644
--- a/errors.go
+++ b/errors.go
@@ -23,4 +23,6 @@ var (
 	ErrUnitNotRunning = errors.New("Unit isn't running")
 	// ErrBusFailure means $DBUS_SESSION_BUS_ADDRESS and $XDG_RUNTIME_DIR were not defined
 	ErrBusFailure = errors.New("Failure to connect to bus, did you run in usermode as root?")
+	// ErrValueNotSet means an expected value is unavailable, but the unit may be running
+	ErrValueNotSet = errors.New("Value not set or unavailable")
 )
diff --git a/helpers.go b/helpers.go
index 390ee26..f5b0605 100644
--- a/helpers.go
+++ b/helpers.go
@@ -30,6 +30,9 @@ func GetMemoryUsage(ctx context.Context, unit string, opts Options) (int, error)
 	if err != nil {
 		return -1, err
 	}
+	if value == "[not set]" {
+		return -1, ErrValueNotSet
+	}
 	return strconv.Atoi(value)
 }
 
diff --git a/helpers_test.go b/helpers_test.go
index 8289f01..a021ced 100644
--- a/helpers_test.go
+++ b/helpers_test.go
@@ -9,7 +9,7 @@ import (
 
 // Testing assumptions
 // - there's no unit installed named `nonexistant`
-// - the syncthing unit to be available on the tester's system.
+// - the syncthing unit is available but the binary is not on the tester's system
 //   this is just what was available on mine, should you want to change it,
 //   either to something in this repo or more common, feel free to submit a PR.
 // - your 'user' isn't root
@@ -23,7 +23,6 @@ func TestGetStartTime(t *testing.T) {
 		runAsUser bool
 	}{
 		// Run these tests only as a user
-
 		//try nonexistant unit in user mode as user
 		{"nonexistant", ErrUnitNotRunning, Options{usermode: false}, true},
 		// try existing unit in user mode as user
@@ -56,7 +55,7 @@ func TestGetStartTime(t *testing.T) {
 		})
 	}
 	// Prove start time changes after a restart
-	t.Run(fmt.Sprintf("Prove start time changes"), func(t *testing.T) {
+	t.Run(fmt.Sprintf("prove start time changes"), func(t *testing.T) {
 		if userString != "root" && userString != "system" {
 			t.Skip("skipping superuser test while running as user")
 		}
@@ -83,6 +82,105 @@ func TestGetStartTime(t *testing.T) {
 
 }
 
-// GetStartTime(ctx context.Context, unit string, opts Options) (time.Time, error) {
+func TestGetMemoryUsage(t *testing.T) {
+	testCases := []struct {
+		unit      string
+		err       error
+		opts      Options
+		runAsUser bool
+	}{
+		// Run these tests only as a user
+
+		//try nonexistant unit in user mode as user
+		{"nonexistant", ErrValueNotSet, Options{usermode: false}, true},
+		// try existing unit in user mode as user
+		{"syncthing", ErrValueNotSet, Options{usermode: true}, true},
+		// try existing unit in system mode as user
+		{"nginx", nil, Options{usermode: false}, true},
+
+		// Run these tests only as a superuser
+
+		// try nonexistant unit in system mode as system
+		{"nonexistant", ErrValueNotSet, Options{usermode: false}, false},
+		// try existing unit in system mode as system
+		{"nginx", ErrBusFailure, Options{usermode: true}, false},
+		// try existing unit in system mode as system
+		{"nginx", nil, Options{usermode: false}, false},
+	}
+	for _, tc := range testCases {
+		t.Run(fmt.Sprintf("%s as %s", tc.unit, userString), func(t *testing.T) {
+			if (userString == "root" || userString == "system") && tc.runAsUser {
+				t.Skip("skipping user test while running as superuser")
+			} else if (userString != "root" && userString != "system") && !tc.runAsUser {
+				t.Skip("skipping superuser test while running as user")
+			}
+			ctx, cancel := context.WithTimeout(context.Background(), 1*time.Second)
+			defer cancel()
+			_, err := GetMemoryUsage(ctx, tc.unit, tc.opts)
+			if err != tc.err {
+				t.Errorf("error is %v, but should have been %v", err, tc.err)
+			}
+		})
+	}
+	// Prove start time changes after a restart
+	t.Run(fmt.Sprintf("prove start time changes"), func(t *testing.T) {
+		ctx, cancel := context.WithTimeout(context.Background(), 1*time.Second)
+		defer cancel()
+		bytes, err := GetMemoryUsage(ctx, "nginx", Options{usermode: false})
+		if err != nil {
+			t.Errorf("issue getting memory usage of nginx: %v", err)
+		}
+		secondBytes, err := GetMemoryUsage(ctx, "user.slice", Options{usermode: false})
+		if err != nil {
+			t.Errorf("issue getting second memort usage reading of nginx: %v", err)
+		}
+		if bytes == secondBytes {
+			t.Errorf("Expected memory usage between nginx and user.slice to differ, but both were: %d", bytes)
+		}
+	})
+
+}
+func TestGetPID(t *testing.T) {
+	testCases := []struct {
+		unit      string
+		err       error
+		opts      Options
+		runAsUser bool
+	}{
+		// Run these tests only as a user
+
+		//try nonexistant unit in user mode as user
+		{"nonexistant", nil, Options{usermode: false}, true},
+		// try existing unit in user mode as user
+		{"syncthing", nil, Options{usermode: true}, true},
+		// try existing unit in system mode as user
+		{"nginx", nil, Options{usermode: false}, true},
+
+		// Run these tests only as a superuser
+
+		// try nonexistant unit in system mode as system
+		{"nonexistant", nil, Options{usermode: false}, false},
+		// try existing unit in system mode as system
+		{"nginx", ErrBusFailure, Options{usermode: true}, false},
+		// try existing unit in system mode as system
+		{"nginx", nil, Options{usermode: false}, false},
+	}
+	for _, tc := range testCases {
+		t.Run(fmt.Sprintf("%s as %s", tc.unit, userString), func(t *testing.T) {
+			if (userString == "root" || userString == "system") && tc.runAsUser {
+				t.Skip("skipping user test while running as superuser")
+			} else if (userString != "root" && userString != "system") && !tc.runAsUser {
+				t.Skip("skipping superuser test while running as user")
+			}
+			ctx, cancel := context.WithTimeout(context.Background(), 1*time.Second)
+			defer cancel()
+			_, err := GetPID(ctx, tc.unit, tc.opts)
+			if err != tc.err {
+				t.Errorf("error is %v, but should have been %v", err, tc.err)
+			}
+		})
+	}
+}
+
 // GetMemoryUsage(ctx context.Context, unit string, opts Options) (int, error) {
 // GetPID(ctx context.Context, unit string, opts Options) (int, error) {