diff --git a/caddytls/client.go b/caddytls/client.go
index 70eccc22..97393195 100644
--- a/caddytls/client.go
+++ b/caddytls/client.go
@@ -287,7 +287,12 @@ func (c *ACMEClient) Revoke(name string) error {
 		return err
 	}
 
-	if !storage.SiteExists(name) {
+	siteExists, err := storage.SiteExists(name)
+	if err != nil {
+		return err
+	}
+
+	if !siteExists {
 		return errors.New("no certificate and key for " + name)
 	}
 
diff --git a/caddytls/config.go b/caddytls/config.go
index f1dcff84..ab793552 100644
--- a/caddytls/config.go
+++ b/caddytls/config.go
@@ -138,7 +138,12 @@ func (c *Config) obtainCertName(name string, allowPrompts bool) error {
 		return err
 	}
 
-	if !c.Managed || !HostQualifies(name) || storage.SiteExists(name) {
+	siteExists, err := storage.SiteExists(name)
+	if err != nil {
+		return err
+	}
+
+	if !c.Managed || !HostQualifies(name) || siteExists {
 		return nil
 	}
 
diff --git a/caddytls/config_test.go b/caddytls/config_test.go
index 7152d76d..f5450bb7 100644
--- a/caddytls/config_test.go
+++ b/caddytls/config_test.go
@@ -115,7 +115,7 @@ func TestStorageForCustomNil(t *testing.T) {
 
 type fakeStorage string
 
-func (s fakeStorage) SiteExists(domain string) bool {
+func (s fakeStorage) SiteExists(domain string) (bool, error) {
 	panic("no impl")
 }
 
diff --git a/caddytls/filestorage.go b/caddytls/filestorage.go
index 32d001fa..bb86958a 100644
--- a/caddytls/filestorage.go
+++ b/caddytls/filestorage.go
@@ -121,16 +121,19 @@ func (s FileStorage) readFile(file string) ([]byte, error) {
 
 // SiteExists implements Storage.SiteExists by checking for the presence of
 // cert and key files.
-func (s FileStorage) SiteExists(domain string) bool {
+func (s FileStorage) SiteExists(domain string) (bool, error) {
 	_, err := os.Stat(s.siteCertFile(domain))
-	if err != nil {
-		return false
+	if os.IsNotExist(err) {
+		return false, nil
+	} else if err != nil {
+		return false, err
 	}
+
 	_, err = os.Stat(s.siteKeyFile(domain))
 	if err != nil {
-		return false
+		return false, err
 	}
-	return true
+	return true, nil
 }
 
 // LoadSite implements Storage.LoadSite by loading it from disk. If it is not
diff --git a/caddytls/storage.go b/caddytls/storage.go
index e3336794..d2c1ff65 100644
--- a/caddytls/storage.go
+++ b/caddytls/storage.go
@@ -39,7 +39,7 @@ type Storage interface {
 	// SiteExists returns true if this site exists in storage.
 	// Site data is considered present when StoreSite has been called
 	// successfully (without DeleteSite having been called, of course).
-	SiteExists(domain string) bool
+	SiteExists(domain string) (bool, error)
 
 	// LoadSite obtains the site data from storage for the given domain and
 	// returns it. If data for the domain does not exist, the
diff --git a/caddytls/storagetest/memorystorage.go b/caddytls/storagetest/memorystorage.go
index cc1a48b5..138342d5 100644
--- a/caddytls/storagetest/memorystorage.go
+++ b/caddytls/storagetest/memorystorage.go
@@ -49,9 +49,9 @@ func NewInMemoryStorage() *InMemoryStorage {
 }
 
 // SiteExists implements caddytls.Storage.SiteExists in memory.
-func (s *InMemoryStorage) SiteExists(domain string) bool {
+func (s *InMemoryStorage) SiteExists(domain string) (bool, error) {
 	_, siteExists := s.Sites[domain]
-	return siteExists
+	return siteExists, nil
 }
 
 // Clear completely clears all values associated with this storage.
diff --git a/caddytls/storagetest/storagetest.go b/caddytls/storagetest/storagetest.go
index 0400aded..9c11d77b 100644
--- a/caddytls/storagetest/storagetest.go
+++ b/caddytls/storagetest/storagetest.go
@@ -113,7 +113,12 @@ func (s *StorageTest) TestSiteExists() error {
 	defer s.runPostTest()
 
 	// Should not exist at first
-	if s.SiteExists("example.com") {
+	siteExists, err := s.SiteExists("example.com")
+	if err != nil {
+		return err
+	}
+
+	if siteExists {
 		return errors.New("Site should not exist")
 	}
 
@@ -121,7 +126,13 @@ func (s *StorageTest) TestSiteExists() error {
 	if err := s.StoreSite("example.com", simpleSiteData); err != nil {
 		return err
 	}
-	if !s.SiteExists("example.com") {
+
+	siteExists, err = s.SiteExists("example.com")
+	if err != nil {
+		return err
+	}
+
+	if !siteExists {
 		return errors.New("Expected site to exist")
 	}
 
@@ -129,7 +140,13 @@ func (s *StorageTest) TestSiteExists() error {
 	if err := s.DeleteSite("example.com"); err != nil {
 		return err
 	}
-	if s.SiteExists("example.com") {
+
+	siteExists, err = s.SiteExists("example.com")
+	if err != nil {
+		return err
+	}
+
+	if siteExists {
 		return errors.New("Site should not exist after delete")
 	}
 	return nil
diff --git a/caddytls/tls_test.go b/caddytls/tls_test.go
index 89b22aca..fb7d59dc 100644
--- a/caddytls/tls_test.go
+++ b/caddytls/tls_test.go
@@ -135,11 +135,16 @@ func TestExistingCertAndKey(t *testing.T) {
 
 	domain := "example.com"
 
-	if storage.SiteExists(domain) {
+	siteExists, err := storage.SiteExists(domain)
+	if err != nil {
+		t.Fatalf("Could not determine whether site exists: %v", err)
+	}
+
+	if siteExists {
 		t.Errorf("Did NOT expect %v to have existing cert or key, but it did", domain)
 	}
 
-	err := saveCertResource(storage, acme.CertificateResource{
+	err = saveCertResource(storage, acme.CertificateResource{
 		Domain:      domain,
 		PrivateKey:  []byte("key"),
 		Certificate: []byte("cert"),
@@ -148,7 +153,12 @@ func TestExistingCertAndKey(t *testing.T) {
 		t.Fatalf("Expected no error, got: %v", err)
 	}
 
-	if !storage.SiteExists(domain) {
+	siteExists, err = storage.SiteExists(domain)
+	if err != nil {
+		t.Fatalf("Could not determine whether site exists: %v", err)
+	}
+
+	if !siteExists {
 		t.Errorf("Expected %v to have existing cert and key, but it did NOT", domain)
 	}
 }