diff --git a/src/addon/md5.cpp b/src/addon/md5.cpp
index 007e6c4efb..01e6717b7f 100644
--- a/src/addon/md5.cpp
+++ b/src/addon/md5.cpp
@@ -158,7 +158,11 @@ std::string MD5::hex_digest() {
 
   finalize();
 
-  for (i=0; i<16; i++) snprintf(s+i*2, sizeof(s+i*2), "%02x", digest[i]);
+  for (i=0; i<16; i++)
+  {
+    char* so = s + i * 2;
+    snprintf(so, sizeof(so), "%02x", digest[i]);
+  }
 
   s[32]='\0';