diff --git a/lib/solr_wrapper/instance.rb b/lib/solr_wrapper/instance.rb
index a227857..64d4291 100644
--- a/lib/solr_wrapper/instance.rb
+++ b/lib/solr_wrapper/instance.rb
@@ -59,11 +59,15 @@ def version
     end
 
     def wrap(&_block)
-      extract_and_configure
-      start
-      yield self
-    ensure
-      stop
+      raise "There is a Solr instance already running on port #{port}." if started?
+
+      begin
+        extract_and_configure
+        start
+        yield self
+      ensure
+        stop
+      end
     end
 
     ##