diff --git a/lib/x11/ext/big-requests.js b/lib/x11/ext/big-requests.js
index 7e24cbb..19b61e9 100644
--- a/lib/x11/ext/big-requests.js
+++ b/lib/x11/ext/big-requests.js
@@ -7,7 +7,7 @@ exports.requireExt = function(display, callback)
     X.QueryExtension('BIG-REQUESTS', function(err, ext) {  
         
         if (!ext.present)
-            callback(new Error('extension not available'));
+            return callback(new Error('extension not available'));
 
         ext.Enable = function( cb )
         {
diff --git a/lib/x11/ext/composite.js b/lib/x11/ext/composite.js
index 7a41030..7e739de 100644
--- a/lib/x11/ext/composite.js
+++ b/lib/x11/ext/composite.js
@@ -20,7 +20,7 @@ exports.requireExt = function(display, callback)
     X.QueryExtension('Composite', function(err, ext) {  
 
         if (!ext.present)
-            callback(new Error('extension not available'));
+            return callback(new Error('extension not available'));
 
         ext.Redirect = { 
             Automatic: 0,
diff --git a/lib/x11/ext/render.js b/lib/x11/ext/render.js
index cfe6914..71dd6db 100644
--- a/lib/x11/ext/render.js
+++ b/lib/x11/ext/render.js
@@ -22,7 +22,7 @@ exports.requireExt = function(display, callback)
 
             if (!ext.present)
             {
-                callback(new Error('extension not available'));
+                return callback(new Error('extension not available'));
             }
         
             ext.QueryVersion = function(clientMaj, clientMin, callback)
diff --git a/lib/x11/ext/shape.js b/lib/x11/ext/shape.js
index 8374c15..acb54ba 100644
--- a/lib/x11/ext/shape.js
+++ b/lib/x11/ext/shape.js
@@ -17,7 +17,7 @@ exports.requireExt = function(display, callback)
     X.QueryExtension('SHAPE', function(err, ext) {  
 
         if (!ext.present)
-            callback(new Error('extension not available'));
+            return callback(new Error('extension not available'));
 
         ext.Kind = { 
             Bounding: 0,
diff --git a/lib/x11/ext/xc-misc.js b/lib/x11/ext/xc-misc.js
index c15fb8d..1f0bc42 100644
--- a/lib/x11/ext/xc-misc.js
+++ b/lib/x11/ext/xc-misc.js
@@ -9,7 +9,7 @@ exports.requireExt = function(display, callback)
     X.QueryExtension('XC-MISC', function(err, ext) {  
 
         if (!ext.present)
-            callback(new Error('extension not available'));
+            return callback(new Error('extension not available'));
 
         ext.QueryVersion = function(clientMaj, clientMin, cb)
         {