diff --git a/PS.g4 b/PS.g4
index 36735aa..8cd1ef4 100644
--- a/PS.g4
+++ b/PS.g4
@@ -11,8 +11,6 @@ SUB: '-';
 MUL: '*';
 DIV: '/';
 
-EXP: '**';
-
 L_PAREN: '(';
 R_PAREN: ')';
 L_BRACE: '{';
@@ -115,8 +113,7 @@ eval_at_sup:
     R_BRACE;
 
 exp:
-    exp EXP exp
-    | exp CARET L_BRACE expr R_BRACE subexpr?
+    exp CARET (atom | L_BRACE expr R_BRACE) subexpr?
     | comp;
 
 comp:
diff --git a/process_latex.py b/process_latex.py
index 1625486..89e74b6 100644
--- a/process_latex.py
+++ b/process_latex.py
@@ -174,11 +174,11 @@ def convert_postfix(postfix):
 
 def convert_exp(exp):
     if exp.exp():
-        base = convert_exp(exp.exp(0))
+        base = convert_exp(exp.exp())
         if isinstance(base, list):
             raise Exception("Cannot raise derivative to power")
-        if exp.EXP():
-            exponent = convert_exp(exp.exp(1))
+        if exp.atom():
+            exponent = convert_atom(exp.atom())
         elif exp.expr():
             exponent = convert_expr(exp.expr())
         return sympy.Pow(base, exponent, evaluate=False)