diff --git a/locale-helper/allow_caller.go b/locale-helper/allow_caller.go
index ddc3492..eadcdf8 100644
--- a/locale-helper/allow_caller.go
+++ b/locale-helper/allow_caller.go
@@ -73,6 +73,7 @@ type allowCallerRegistry struct {
 	privilegedGroupID uint32
 	processGroups     func(uint32) ([]uint32, error)
 	processParent     func(uint32) (uint32, error)
+	processStartTime func(uint32) (uint64, error)
 
 	mu        sync.RWMutex
 	callers   map[string]callerInfo
@@ -128,6 +129,7 @@ func newAllowCallerRegistryWithConfig(service allowCallerBus, stateFile string,
 		busID:             busID,
 		privilegedGroupID: privilegedGroupID,
 		processGroups:     getProcessGroups,
+		processStartTime: getProcessStartTime,
 		processParent:     getProcessParentPID,
 		callers:           make(map[string]callerInfo),
 	}, nil
@@ -336,7 +338,7 @@ func (r *allowCallerRegistry) authorizeRegistrar(sender dbus.Sender, uniqueName
 	}
 
 	// Capture starttime before reading /proc to detect PID reuse (TOCTOU mitigation).
-	senderStartTime, err := getProcessStartTime(senderPID)
+	senderStartTime, err := r.processStartTime(senderPID)
 	if err != nil {
 		return fmt.Errorf("get sender %s start time failed: %w", sender, err)
 	}
@@ -347,7 +349,7 @@ func (r *allowCallerRegistry) authorizeRegistrar(sender dbus.Sender, uniqueName
 	}
 
 	// Verify PID was not recycled during /proc access.
-	checkStartTime, err := getProcessStartTime(senderPID)
+	checkStartTime, err := r.processStartTime(senderPID)
 	if err != nil || checkStartTime != senderStartTime {
 		return fmt.Errorf("sender %s PID %d reused during authorization", sender, senderPID)
 	}
diff --git a/locale-helper/allow_caller_test.go b/locale-helper/allow_caller_test.go
index cc8cebc..c414e6b 100644
--- a/locale-helper/allow_caller_test.go
+++ b/locale-helper/allow_caller_test.go
@@ -322,6 +322,9 @@ func TestAddCallerAuthorizedSender(t *testing.T) {
 
 	r := newRegistryForTest(t, bus)
 	r.privilegedGroupID = 42
+	r.processStartTime = func(pid uint32) (uint64, error) {
+		return 12345, nil
+	}
 	r.processGroups = func(pid uint32) ([]uint32, error) {
 		return []uint32{42}, nil
 	}
@@ -604,6 +607,9 @@ func TestAuthorizeRegistrar(t *testing.T) {
 		bus.connPID[":1.0"] = 5
 		r := newRegistryForTest(t, bus)
 		r.privilegedGroupID = 42
+		r.processStartTime = func(pid uint32) (uint64, error) {
+			return 12345, nil
+		}
 		r.processGroups = func(pid uint32) ([]uint32, error) {
 			return []uint32{99}, nil
 		}
@@ -619,6 +625,9 @@ func TestAuthorizeRegistrar(t *testing.T) {
 		bus.connUID[":1.100"] = 2000
 		r := newRegistryForTest(t, bus)
 		r.privilegedGroupID = 42
+		r.processStartTime = func(pid uint32) (uint64, error) {
+			return 12345, nil
+		}
 		r.processGroups = func(pid uint32) ([]uint32, error) {
 			return []uint32{42}, nil
 		}
@@ -635,6 +644,9 @@ func TestAuthorizeRegistrar(t *testing.T) {
 		bus.connPID[":1.100"] = 10
 		r := newRegistryForTest(t, bus)
 		r.privilegedGroupID = 42
+		r.processStartTime = func(pid uint32) (uint64, error) {
+			return 12345, nil
+		}
 		r.processGroups = func(pid uint32) ([]uint32, error) {
 			return []uint32{42}, nil
 		}
@@ -662,6 +674,9 @@ func TestAuthorizeRegistrar(t *testing.T) {
 		bus.connPID[":1.100"] = 10
 		r := newRegistryForTest(t, bus)
 		r.privilegedGroupID = 42
+		r.processStartTime = func(pid uint32) (uint64, error) {
+			return 12345, nil
+		}
 		r.processGroups = func(pid uint32) ([]uint32, error) {
 			return []uint32{42}, nil
 		}