diff --git a/lib/codabar.js b/lib/codabar.js
index 179e866..674ba4f 100644
--- a/lib/codabar.js
+++ b/lib/codabar.js
@@ -2,7 +2,7 @@
  * barcode generator - codabar
  */
 
-var gm = require('gm');
+var gm = require('gm').subClass({ imageMagick: true });
 
 var bmap = {
 	'0': [0,0,0,0,0,1,1],
diff --git a/lib/code128.js b/lib/code128.js
index 46bde12..bd09e41 100644
--- a/lib/code128.js
+++ b/lib/code128.js
@@ -2,7 +2,7 @@
  * barcode generator - code128
  */
 
-var gm = require('gm');
+var gm = require('gm').subClass({ imageMagick: true });
 
 const BARMAP = [
   [2,1,2,2,2,2], [2,2,2,1,2,2], [2,2,2,2,2,1], [1,2,1,2,2,3], [1,2,1,3,2,2],
diff --git a/lib/code39.js b/lib/code39.js
index 0004535..a7c9dd0 100644
--- a/lib/code39.js
+++ b/lib/code39.js
@@ -2,7 +2,7 @@
  * barcode generator - code39
  */
 
-var gm = require('gm');
+var gm = require('gm').subClass({ imageMagick: true });
 
 const bmap = {
 	' ': [0,1,1,0,0,0,1,0,0],
diff --git a/lib/ean13.js b/lib/ean13.js
index c7e3276..b9fdee4 100644
--- a/lib/ean13.js
+++ b/lib/ean13.js
@@ -2,7 +2,7 @@
  * barcode generator - EAN13 (ISBN)
  */
 
-var gm = require('gm'),
+var gm = require('gm').subClass({ imageMagick: true }),
   getCheckDigit = require('./utils/checksums').weight3even10,
   Barcode1D = require('./utils/draw1D');
 
diff --git a/lib/upc-a.js b/lib/upc-a.js
index c49a55c..5d4463e 100644
--- a/lib/upc-a.js
+++ b/lib/upc-a.js
@@ -2,7 +2,7 @@
  * barcode generator - UPC-A
  */
 
-var gm = require('gm'),
+var gm = require('gm').subClass({ imageMagick: true }),
   getCheckDigit = require('./utils/checksums').weight3odd10,
   Barcode1D = require('./utils/draw1D');
 
diff --git a/lib/utils/draw1D.js b/lib/utils/draw1D.js
index 11bac91..bfc0bb8 100644
--- a/lib/utils/draw1D.js
+++ b/lib/utils/draw1D.js
@@ -6,7 +6,7 @@
  * not rely on it, rather please use the Barcode2D drawer instead.
  */
 
-var gm = require('gm');
+var gm = require('gm').subClass({ imageMagick: true });
 
 const MODE_BINARY = 0;
 const MODE_BARWIDTH = 1;
diff --git a/lib/utils/draw2D.js b/lib/utils/draw2D.js
index 92e8636..e7e201d 100644
--- a/lib/utils/draw2D.js
+++ b/lib/utils/draw2D.js
@@ -28,7 +28,7 @@
  * your baseheight.
  */
 
-var gm = require('gm');
+var gm = require('gm').subClass({ imageMagick: true });
 
 /*
  * Basic constructor