diff --git a/restream/restream.go b/restream/restream.go
index e58eaf00..abde48a0 100644
--- a/restream/restream.go
+++ b/restream/restream.go
@@ -30,28 +30,28 @@ import (
 type Restreamer interface {
 	ID() string                                                // ID of this instance
 	Name() string                                              // Arbitrary name of this instance
-	CreatedAt() time.Time                                      // time of when this instance has been created
-	Start()                                                    // start all processes that have a "start" order
-	Stop()                                                     // stop all running process but keep their "start" order
-	AddProcess(config *app.Config) error                       // add a new process
-	GetProcessIDs(idpattern, refpattern string) []string       // get a list of process IDs based on patterns for ID and reference
-	DeleteProcess(id string) error                             // delete a process
-	UpdateProcess(id string, config *app.Config) error         // update a process
-	StartProcess(id string) error                              // start a process
-	StopProcess(id string) error                               // stop a process
-	RestartProcess(id string) error                            // restart a process
-	ReloadProcess(id string) error                             // reload a process
-	GetProcess(id string) (*app.Process, error)                // get a process
-	GetProcessState(id string) (*app.State, error)             // get the state of a process
-	GetProcessLog(id string) (*app.Log, error)                 // get the logs of a process
-	GetPlayout(id, inputid string) (string, error)             // get the URL of the playout API for a process
-	Probe(id string) app.Probe                                 // probe a process
-	Skills() skills.Skills                                     // get the ffmpeg skills
-	ReloadSkills() error                                       // reload the ffmpeg skills
-	SetProcessMetadata(id, key string, data interface{}) error // set metatdata to a process
-	GetProcessMetadata(id, key string) (interface{}, error)    // get previously set metadata from a process
-	SetMetadata(key string, data interface{}) error            // set general metadata
-	GetMetadata(key string) (interface{}, error)               // get previously set general metadata
+	CreatedAt() time.Time                                      // Time of when this instance has been created
+	Start()                                                    // Start all processes that have a "start" order
+	Stop()                                                     // Stop all running process but keep their "start" order
+	AddProcess(config *app.Config) error                       // Add a new process
+	GetProcessIDs(idpattern, refpattern string) []string       // Get a list of process IDs based on patterns for ID and reference
+	DeleteProcess(id string) error                             // Delete a process
+	UpdateProcess(id string, config *app.Config) error         // Update a process
+	StartProcess(id string) error                              // Start a process
+	StopProcess(id string) error                               // Stop a process
+	RestartProcess(id string) error                            // Restart a process
+	ReloadProcess(id string) error                             // Reload a process
+	GetProcess(id string) (*app.Process, error)                // Get a process
+	GetProcessState(id string) (*app.State, error)             // Get the state of a process
+	GetProcessLog(id string) (*app.Log, error)                 // Get the logs of a process
+	GetPlayout(id, inputid string) (string, error)             // Get the URL of the playout API for a process
+	Probe(id string) app.Probe                                 // Probe a process
+	Skills() skills.Skills                                     // Get the ffmpeg skills
+	ReloadSkills() error                                       // Reload the ffmpeg skills
+	SetProcessMetadata(id, key string, data interface{}) error // Set metatdata to a process
+	GetProcessMetadata(id, key string) (interface{}, error)    // Get previously set metadata from a process
+	SetMetadata(key string, data interface{}) error            // Set general metadata
+	GetMetadata(key string) (interface{}, error)               // Get previously set general metadata
 }
 
 // Config is the required configuration for a new restreamer instance.
@@ -1304,6 +1304,8 @@ func (r *restream) GetPlayout(id, inputid string) (string, error) {
 	return "127.0.0.1:" + strconv.Itoa(port), nil
 }
 
+var ErrMetadataKeyNotFound = errors.New("unknown key")
+
 func (r *restream) SetProcessMetadata(id, key string, data interface{}) error {
 	r.lock.Lock()
 	defer r.lock.Unlock()
@@ -1350,11 +1352,11 @@ func (r *restream) GetProcessMetadata(id, key string) (interface{}, error) {
 	}
 
 	data, ok := task.metadata[key]
-	if ok {
-		return data, nil
+	if !ok {
+		return nil, ErrMetadataKeyNotFound
 	}
 
-	return nil, nil
+	return data, nil
 }
 
 func (r *restream) SetMetadata(key string, data interface{}) error {
@@ -1393,9 +1395,9 @@ func (r *restream) GetMetadata(key string) (interface{}, error) {
 	}
 
 	data, ok := r.metadata[key]
-	if ok {
-		return data, nil
+	if !ok {
+		return nil, ErrMetadataKeyNotFound
 	}
 
-	return nil, nil
+	return data, nil
 }