diff --git a/src/variable.cpp b/src/variable.cpp
index fdef9985bf..376cc8045a 100644
--- a/src/variable.cpp
+++ b/src/variable.cpp
@@ -384,7 +384,7 @@ void Variable::set(int narg, char **arg)
     num[nvar] = 3;
     which[nvar] = 0;
     pad[nvar] = 0;
-    if (!utils::strmatch(arg[2],"%[0-9 ]*\\.[0-9]+[efgEFG]"))
+    if (!utils::strmatch(arg[3],"%[0-9 ]*\\.[0-9]+[efgEFG]"))
       error->all(FLERR,"Incorrect conversion in format string");
     data[nvar] = new char*[num[nvar]];
     copy(2,&arg[2],data[nvar]);