diff --git a/pkg/source/firefly/config.go b/pkg/source/firefly/config.go
index 9c51370..1f759f2 100644
--- a/pkg/source/firefly/config.go
+++ b/pkg/source/firefly/config.go
@@ -104,7 +104,7 @@ where the devices are exported but they are still valid on the firefly server
 func (c *Config) Initialize(src source.Config) error {
 	c.src = src
 
-	if apiKey := os.Getenv("FIREFLY_API_KEY"); apiKey == "" && c.APIKey == "" {
+	if apiKey := os.Getenv("FIREFLY_API_KEY"); apiKey != "" && c.APIKey == "" {
 		c.APIKey = apiKey
 	}
 	if c.appID == "" {
diff --git a/pkg/source/ttnv2/config.go b/pkg/source/ttnv2/config.go
index 9e5d6e9..33d6d93 100644
--- a/pkg/source/ttnv2/config.go
+++ b/pkg/source/ttnv2/config.go
@@ -114,7 +114,7 @@ func (c *Config) Initialize(rootConfig source.Config) error {
 	if appAccessKey := os.Getenv("TTNV2_APP_ACCESS_KEY"); appAccessKey != "" && c.appAccessKey == "" {
 		c.appAccessKey = appAccessKey
 	}
-	if accountServerClientSecret := os.Getenv("TTNV2_ACCOUNT_SERVER_CLIENT_SECRET"); accountServerClientSecret != "" {
+	if accountServerClientSecret := os.Getenv("TTNV2_ACCOUNT_SERVER_CLIENT_SECRET"); accountServerClientSecret != "" && c.sdkConfig.AccountServerClientSecret == "" {
 		c.sdkConfig.AccountServerClientSecret = accountServerClientSecret
 	}