diff --git a/lib/execjs.rb b/lib/execjs.rb
index 7cd0288..0fd9212 100644
--- a/lib/execjs.rb
+++ b/lib/execjs.rb
@@ -27,7 +27,8 @@ module ExecJS
   end
 
   def self.runtime
-    @runtime ||= Runtimes.best_available
+    @runtime ||= Runtimes.best_available ||
+      raise(ExecJS::RuntimeError, "Could not find a JavaScript runtime")
   end
 
   def self.root
diff --git a/lib/execjs/runtimes.rb b/lib/execjs/runtimes.rb
index 462526b..8079354 100644
--- a/lib/execjs/runtimes.rb
+++ b/lib/execjs/runtimes.rb
@@ -31,7 +31,7 @@ module ExecJS
 
 
     def self.best_available
-      runtimes.find(&:available?) or raise(ExecJS::RuntimeError, 'Could not find any JavaScript runtime!')
+      runtimes.find(&:available?)
     end
 
     def self.runtimes