diff --git a/index.js b/index.js
index 535c8b0..ebf06ef 100644
--- a/index.js
+++ b/index.js
@@ -120,11 +120,9 @@ totp.gen = function(key, opt) {
 
 	// Time has been overwritten.
 	if(opt._t) {
-		console.log('#####################################');
-		console.log('# NOTE: TOTP TIME VARIABLE HAS BEEN #');
-		console.log('# OVERWRITTEN.  THIS SHOULD ONLY BE #');
-		console.log('# USED FOR TEST PURPOSES.           #');
-		console.log('#####################################');
+		if(process.env.NODE_ENV != 'test') {
+			throw new Error('cannot overwrite time in non-test environment!');
+		}
 		_t = opt._t;
 	}
 
@@ -172,11 +170,9 @@ totp.verify = function(token, key, opt) {
 
 	// Time has been overwritten.
 	if(opt._t) {
-		console.log('#####################################');
-		console.log('# NOTE: TOTP TIME VARIABLE HAS BEEN #');
-		console.log('# OVERWRITTEN.  THIS SHOULD ONLY BE #');
-		console.log('# USED FOR TEST PURPOSES.           #');
-		console.log('#####################################');
+		if(process.env.NODE_ENV != 'test') {
+			throw new Error('cannot overwrite time in non-test environment!');
+		}
 		_t = opt._t;
 	}
 
diff --git a/package.json b/package.json
index a42ba8a..5866d18 100644
--- a/package.json
+++ b/package.json
@@ -10,7 +10,7 @@
   },
   "main": "index.js",
   "scripts": {
-    "test": "mocha"
+    "test": "NODE_ENV=test mocha"
   },
   "engines": {
     "node": ">= v0.6.0"