diff --git a/src/common/strvararg.cpp b/src/common/strvararg.cpp
index c448c1fb26..b8c2e8056a 100644
--- a/src/common/strvararg.cpp
+++ b/src/common/strvararg.cpp
@@ -361,7 +361,7 @@ private:
             CopyAllBefore();
         }
 
-        *m_fmtLast = ch;
+        *m_fmtLast++ = ch;
     }
 
     void CopyAllBefore()