diff --git a/src/components/__tests__/FontAwesomeIcon.test.js b/src/components/__tests__/FontAwesomeIcon.test.js
index 619dc8e..832be46 100644
--- a/src/components/__tests__/FontAwesomeIcon.test.js
+++ b/src/components/__tests__/FontAwesomeIcon.test.js
@@ -83,7 +83,7 @@ function rgbToHex (r, g, b) {
 }
 
 function decimalToHex (decimal) {
-  return decimal.toString(16).substr(2, 6)
+  return decimal.toString(16).slice(2, 8)
 }
 
 // react-native-svg changed the way it uses the `fill` attribute across versions. Older versions