diff --git a/command/agent/agent.go b/command/agent/agent.go
index 2b3e85c08d..1b75b56788 100644
--- a/command/agent/agent.go
+++ b/command/agent/agent.go
@@ -646,6 +646,7 @@ func (a *Agent) setupNodeID(config *Config) error {
 	// If they've configured a node ID manually then just use that, as
 	// long as it's valid.
 	if config.NodeID != "" {
+		config.NodeID = types.NodeID(strings.ToLower(string(config.NodeID)))
 		if _, err := uuid.ParseUUID(string(config.NodeID)); err != nil {
 			return err
 		}
@@ -674,6 +675,7 @@ func (a *Agent) setupNodeID(config *Config) error {
 		}
 
 		nodeID := strings.TrimSpace(string(rawID))
+		nodeID = strings.ToLower(nodeID)
 		if _, err := uuid.ParseUUID(nodeID); err != nil {
 			return err
 		}
diff --git a/command/agent/agent_test.go b/command/agent/agent_test.go
index 08b22946c1..d66d9097a5 100644
--- a/command/agent/agent_test.go
+++ b/command/agent/agent_test.go
@@ -341,7 +341,7 @@ func TestAgent_NodeID(t *testing.T) {
 	if err != nil {
 		t.Fatalf("err: %v", err)
 	}
-	c.NodeID = types.NodeID(newID)
+	c.NodeID = types.NodeID(strings.ToUpper(newID))
 	if err := agent.setupNodeID(c); err != nil {
 		t.Fatalf("err: %v", err)
 	}
@@ -361,7 +361,7 @@ func TestAgent_NodeID(t *testing.T) {
 	}
 
 	// Set a valid ID via the file.
-	if err := ioutil.WriteFile(fileID, []byte("adf4238a-882b-9ddc-4a9d-5b6758e4159e"), 0600); err != nil {
+	if err := ioutil.WriteFile(fileID, []byte("ADF4238a-882b-9ddc-4a9d-5b6758e4159e"), 0600); err != nil {
 		t.Fatalf("err: %v", err)
 	}
 	c.NodeID = ""