diff --git a/src/core_read.cpp b/src/core_read.cpp
index 0eba29a5cd..a98e9e046a 100644
--- a/src/core_read.cpp
+++ b/src/core_read.cpp
@@ -16,7 +16,6 @@
 #include <version.h>
 
 #include <boost/algorithm/string/classification.hpp>
-#include <boost/algorithm/string/replace.hpp>
 #include <boost/algorithm/string/split.hpp>
 
 #include <algorithm>
@@ -41,8 +40,9 @@ CScript ParseScript(const std::string& s)
             std::string strName(name);
             mapOpNames[strName] = static_cast<opcodetype>(op);
             // Convenience: OP_ADD and just ADD are both recognized:
-            boost::algorithm::replace_first(strName, "OP_", "");
-            mapOpNames[strName] = static_cast<opcodetype>(op);
+            if (strName.compare(0, 3, "OP_") == 0) {  // strName starts with "OP_"
+                mapOpNames[strName.substr(3)] = static_cast<opcodetype>(op);
+            }
         }
     }