diff --git a/lib/jasmine-core/jasmine.js b/lib/jasmine-core/jasmine.js
index 84548dd6..63e9a9a9 100644
--- a/lib/jasmine-core/jasmine.js
+++ b/lib/jasmine-core/jasmine.js
@@ -1,4 +1,4 @@
-var isCommonJS = typeof window == "undefined";
+var isCommonJS = typeof window == "undefined" && typeof exports == "object";
 
 /**
  * Top level namespace for Jasmine, a lightweight JavaScript BDD/spec/testing framework.
diff --git a/src/core/base.js b/src/core/base.js
index a4afea98..40d38aed 100644
--- a/src/core/base.js
+++ b/src/core/base.js
@@ -1,4 +1,4 @@
-var isCommonJS = typeof window == "undefined";
+var isCommonJS = typeof window == "undefined" && typeof exports == "object";
 
 /**
  * Top level namespace for Jasmine, a lightweight JavaScript BDD/spec/testing framework.