diff --git a/stack/maxima/contrib/validators.mac b/stack/maxima/contrib/validators.mac
index 9d82e9d9e8d810b9254377f68a7cdee77a883f43..46a2a89057aa2d0418e5a0ba8b7f54086b1a3978 100644
--- a/stack/maxima/contrib/validators.mac
+++ b/stack/maxima/contrib/validators.mac
@@ -33,7 +33,6 @@ s_test_case(validate_underscore(1+a1), "");
 s_test_case(validate_underscore(1+a_1), "Underscore characters are not permitted in this input.");
 
 /* The student may not use a user-defined function, or arrays, anywhere in their input. */
-
 validate_nofunctions(ex):= block([op1],
   if atom(ex) then return(""),
   op1:ev(op(ex)),
@@ -49,3 +48,12 @@ s_test_case(validate_nofunctions(x(2)), "User-defined functions are not permitte
 s_test_case(validate_nofunctions(x(t)), "User-defined functions are not permitted in this input.");
 s_test_case(validate_nofunctions(1+f(x+1)), "User-defined functions are not permitted in this input.");
 
+/* The student may only use single-character variable names in their answer. */
+/* This is intended for use when Insert Stars is turned off, but we still want to indicate to students that they may have forgotten a star */
+validate_all_one_letter_variables(ex) := if not(is(ev(lmax(map(lambda([ex2],slength(string(ex2))),listofvars(ex))),simp)>1)) then ""
+        else "Only single-character variable names are permitted in this input. Perhaps you forgot to use an asterisk (*) somewhere, or perhaps you used a Greek letter.";
+
+s_test_case(validate_all_one_letter_variables(1), "");
+s_test_case(validate_all_one_letter_variables((A*x+B)/(x^2+1) + C/x), "");
+s_test_case(validate_all_one_letter_variables((Ax+B)/(x^2+1) + C/x), "Only single-character variable names are permitted in this input. Perhaps you forgot to use an asterisk (*) somewhere, or perhaps you used a Greek letter.");
+s_test_case(validate_all_one_letter_variables((theta*x+B)/(x^2+1) + C/x), "Only single-character variable names are permitted in this input. Perhaps you forgot to use an asterisk (*) somewhere, or perhaps you used a Greek letter.");