diff --git a/src/input.cpp b/src/input.cpp
index 814f900fbd..377df97e87 100644
--- a/src/input.cpp
+++ b/src/input.cpp
@@ -610,7 +610,7 @@ void Input::substitute(char *&str, char *&str2, int &max, int &max2, int flag)
 
         while (var[i] != '\0' && var[i] != '}') i++;
 
-        if (var[i] == '\0') error->one(FLERR,"Invalid variable name");
+        if (var[i] == '\0') error->one(FLERR,"Invalid variable name {}", var);
         var[i] = '\0';
         beyond = ptr + strlen(var) + 3;
         value = variable->retrieve(var);