diff --git a/internal/envconfig/envconfig.go b/internal/envconfig/envconfig.go
index 00abc7c2beb0..452985f8d8f1 100644
--- a/internal/envconfig/envconfig.go
+++ b/internal/envconfig/envconfig.go
@@ -45,7 +45,7 @@ var (
 	// option is present for backward compatibility. This option may be overridden
 	// by setting the environment variable "GRPC_ENFORCE_ALPN_ENABLED" to "true"
 	// or "false".
-	EnforceALPNEnabled = boolFromEnv("GRPC_ENFORCE_ALPN_ENABLED", false)
+	EnforceALPNEnabled = boolFromEnv("GRPC_ENFORCE_ALPN_ENABLED", true)
 	// XDSFallbackSupport is the env variable that controls whether support for
 	// xDS fallback is turned on. If this is unset or is false, only the first
 	// xDS server in the list of server configs will be used.