diff --git a/cmd/sops/encrypt.go b/cmd/sops/encrypt.go
index 826fa496a..266f48ae3 100644
--- a/cmd/sops/encrypt.go
+++ b/cmd/sops/encrypt.go
@@ -36,7 +36,8 @@ func (err *fileAlreadyEncryptedError) Error() string {
 
 func (err *fileAlreadyEncryptedError) UserError() string {
 	message := "The file you have provided contains a top-level entry called " +
-		"'sops'. This is generally due to the file already being encrypted. " +
+		"'sops', or for flat file formats top-level entries starting with " +
+		"'sops_'. This is generally due to the file already being encrypted. " +
 		"SOPS uses a top-level entry called 'sops' to store the metadata " +
 		"required to decrypt the file. For this reason, SOPS can not " +
 		"encrypt files that already contain such an entry.\n\n" +
@@ -47,10 +48,8 @@ func (err *fileAlreadyEncryptedError) UserError() string {
 }
 
 func ensureNoMetadata(opts encryptOpts, branch sops.TreeBranch) error {
-	for _, b := range branch {
-		if b.Key == "sops" {
-			return &fileAlreadyEncryptedError{}
-		}
+	if opts.OutputStore.HasSopsTopLevelKey(branch) {
+		return &fileAlreadyEncryptedError{}
 	}
 	return nil
 }
diff --git a/sops.go b/sops.go
index c144db005..672d32499 100644
--- a/sops.go
+++ b/sops.go
@@ -567,6 +567,12 @@ type ValueEmitter interface {
 	EmitValue(interface{}) ([]byte, error)
 }
 
+// CheckEncryped is the interface for testing whether a branch contains sops
+// metadata. This is used to check whether a file is already encrypted or not.
+type CheckEncryped interface {
+	HasSopsTopLevelKey(TreeBranch) bool
+}
+
 // Store is used to interact with files, both encrypted and unencrypted.
 type Store interface {
 	EncryptedFileLoader
@@ -574,6 +580,7 @@ type Store interface {
 	EncryptedFileEmitter
 	PlainFileEmitter
 	ValueEmitter
+	CheckEncryped
 }
 
 // MasterKeyCount returns the number of master keys available
diff --git a/stores/dotenv/store.go b/stores/dotenv/store.go
index 9433322ee..88eb0442f 100644
--- a/stores/dotenv/store.go
+++ b/stores/dotenv/store.go
@@ -175,3 +175,15 @@ func isComplexValue(v interface{}) bool {
 	}
 	return false
 }
+
+// HasSopsTopLevelKey checks whether a top-level "sops" key exists.
+func (store *Store) HasSopsTopLevelKey(branch sops.TreeBranch) bool {
+	for _, b := range branch {
+		if key, ok := b.Key.(string); ok {
+			if strings.HasPrefix(key, SopsPrefix) {
+				return true
+			}
+		}
+	}
+	return false
+}
diff --git a/stores/dotenv/store_test.go b/stores/dotenv/store_test.go
index c234d4ea5..6886fbc34 100644
--- a/stores/dotenv/store_test.go
+++ b/stores/dotenv/store_test.go
@@ -80,3 +80,20 @@ func TestEmitEncryptedFileStability(t *testing.T) {
 		previous = bytes
 	}
 }
+
+func TestHasSopsTopLevelKey(t *testing.T) {
+	ok := (&Store{}).HasSopsTopLevelKey(sops.TreeBranch{
+		sops.TreeItem{
+			Key:   "sops",
+			Value: "value",
+		},
+	})
+	assert.Equal(t, ok, false)
+	ok = (&Store{}).HasSopsTopLevelKey(sops.TreeBranch{
+		sops.TreeItem{
+			Key:   "sops_",
+			Value: "value",
+		},
+	})
+	assert.Equal(t, ok, true)
+}
diff --git a/stores/ini/store.go b/stores/ini/store.go
index dd1a77c63..c44b89302 100644
--- a/stores/ini/store.go
+++ b/stores/ini/store.go
@@ -274,3 +274,8 @@ func (store *Store) EmitExample() []byte {
 	}
 	return bytes
 }
+
+// HasSopsTopLevelKey checks whether a top-level "sops" key exists.
+func (store *Store) HasSopsTopLevelKey(branch sops.TreeBranch) bool {
+	return stores.HasSopsTopLevelKey(branch)
+}
diff --git a/stores/json/store.go b/stores/json/store.go
index cbecd8362..2f0f7a721 100644
--- a/stores/json/store.go
+++ b/stores/json/store.go
@@ -357,3 +357,13 @@ func (store *Store) EmitExample() []byte {
 	}
 	return bytes
 }
+
+// HasSopsTopLevelKey checks whether a top-level "sops" key exists.
+func (store *Store) HasSopsTopLevelKey(branch sops.TreeBranch) bool {
+	return stores.HasSopsTopLevelKey(branch)
+}
+
+// HasSopsTopLevelKey checks whether a top-level "sops" key exists.
+func (store *BinaryStore) HasSopsTopLevelKey(branch sops.TreeBranch) bool {
+	return stores.HasSopsTopLevelKey(branch)
+}
diff --git a/stores/stores.go b/stores/stores.go
index e4b17289d..f4f8f2354 100644
--- a/stores/stores.go
+++ b/stores/stores.go
@@ -506,3 +506,13 @@ var ExampleFlatTree = sops.Tree{
 		},
 	},
 }
+
+// HasSopsTopLevelKey returns true if the given branch has a top-level key called "sops".
+func HasSopsTopLevelKey(branch sops.TreeBranch) bool {
+	for _, b := range branch {
+		if b.Key == "sops" {
+			return true
+		}
+	}
+	return false
+}
diff --git a/stores/yaml/store.go b/stores/yaml/store.go
index 4d036f366..86ca00672 100644
--- a/stores/yaml/store.go
+++ b/stores/yaml/store.go
@@ -417,3 +417,8 @@ func (store *Store) EmitExample() []byte {
 	}
 	return bytes
 }
+
+// HasSopsTopLevelKey checks whether a top-level "sops" key exists.
+func (store *Store) HasSopsTopLevelKey(branch sops.TreeBranch) bool {
+	return stores.HasSopsTopLevelKey(branch)
+}
diff --git a/stores/yaml/store_test.go b/stores/yaml/store_test.go
index 41b3004d0..fb53d9ed3 100644
--- a/stores/yaml/store_test.go
+++ b/stores/yaml/store_test.go
@@ -380,4 +380,21 @@ func TestIndent1(t *testing.T) {
 	assert.Nil(t, err)
 	assert.Equal(t, string(INDENT_1_OUT), string(bytes))
 	assert.Equal(t, INDENT_1_OUT, bytes)
-}
\ No newline at end of file
+}
+
+func TestHasSopsTopLevelKey(t *testing.T) {
+	ok := (&Store{}).HasSopsTopLevelKey(sops.TreeBranch{
+		sops.TreeItem{
+			Key:   "sops",
+			Value: "value",
+		},
+	})
+	assert.Equal(t, ok, true)
+	ok = (&Store{}).HasSopsTopLevelKey(sops.TreeBranch{
+		sops.TreeItem{
+			Key:   "sops_",
+			Value: "value",
+		},
+	})
+	assert.Equal(t, ok, false)
+}