diff --git a/remix-lib/src/util.js b/remix-lib/src/util.js
index 9b9169da1e..a30b8b9d56 100644
--- a/remix-lib/src/util.js
+++ b/remix-lib/src/util.js
@@ -187,7 +187,8 @@ module.exports = {
     if (code1 === code2) return true
     if (code2 === '0x') return false // abstract contract. see comment
 
-    if (code2.substr(4, 40) === '0000000000000000000000000000000000000000') {
+    if (code2.substr(2, 46) === '7300000000000000000000000000000000000000003014') {
+      // testing the following signature: PUSH20 00..00 ADDRESS EQ
       // in the context of a library, that slot contains the address of the library (pushed by the compiler to avoid calling library other than with a DELEGATECALL)
       // if code2 is not a library, well we still suppose that the comparison remain relevant even if we remove some information from `code1`
       code1 = replaceLibReference(code1, 4)