diff --git a/stl/ast.py b/stl/ast.py
index f65b179..41d9001 100644
--- a/stl/ast.py
+++ b/stl/ast.py
@@ -65,14 +65,11 @@ TOP = _Top()
 BOT = _Bot()
 
 
-class AtomicPred(namedtuple("AP", ["id", "time"]), AST):
+class AtomicPred(namedtuple("AP", ["id"]), AST):
     __slots__ = ()
 
     def __repr__(self):
-        # TODO: fix this hack...
-        if str(self.time) in ("t + dt", "dt + t"):
-            return f"{self.id}'"
-        return f"{self.id}({self.time})"
+        return f"{self.id}"
 
     def children(self):
         return []
@@ -92,14 +89,11 @@ class LinEq(namedtuple("LinEquality", ["terms", "op", "const"]), AST):
         return hash(repr(self))
 
 
-class Var(namedtuple("Var", ["coeff", "id", "time"])):
+class Var(namedtuple("Var", ["coeff", "id"])):
     __slots__ = ()
 
     def __repr__(self):
-        # TODO: fix this hack...
-        if str(self.time) in ("t + dt", "dt + t"):
-            return f"{self.coeff}*{self.id}'"
-        return f"{self.coeff}*{self.id}({self.time})"
+        return f"{self.coeff}*{self.id}"
 
 
 class Interval(namedtuple('I', ['lower', 'upper'])):
diff --git a/stl/parser.py b/stl/parser.py
index 7b716af..38e916a 100644
--- a/stl/parser.py
+++ b/stl/parser.py
@@ -21,7 +21,8 @@ from stl import ast
 from stl.utils import implies, xor, iff, env, alw
 
 STL_GRAMMAR = Grammar(u'''
-phi = (timed_until / until / neg / next / g / f / lineq / AP / or / and / implies / xor / iff / paren_phi)
+phi = (timed_until / until / neg / next / g / f / lineq / AP / or / and
+     / implies / xor / iff / paren_phi)
 
 paren_phi = "(" __ phi __ ")"
 
@@ -31,7 +32,7 @@ implies = paren_phi _ ("→" / "->") _ (and / paren_phi)
 iff = paren_phi _ ("⇔" / "<->" / "iff") _ (and / paren_phi)
 xor = paren_phi _ ("⊕" / "^" / "xor") _ (and / paren_phi)
 
-neg = ("~" / "¬") phi
+neg = ("~" / "¬") paren_phi
 next = "X" paren_phi
 f = F interval? phi
 g = G interval? phi
@@ -51,12 +52,8 @@ term =  coeff? var
 coeff = ((dt __ "*" __)? const __ "*" __) / (dt __ "*")
 terms = (term __ pm __ terms) / term
 
-var = id time?
-time = prime / time_index
-time_index = "(" ("t" / const) ")"
-prime = "'"
-
-AP = id time?
+var = id
+AP = ~r"[a-zA-z\d]+"
 
 pm = "+" / "-"
 dt = "dt"
@@ -135,13 +132,6 @@ class STLVisitor(NodeVisitor):
     def visit_id(self, name, _):
         return Symbol(name.text)
 
-    def visit_var(self, _, children):
-        iden, time_node = children
-
-        time_node = list(flatten(time_node))
-        time = time_node[0] if len(time_node) > 0 else ast.t_sym
-            
-        return iden, time
 
     def visit_time_index(self, _, children):
         children = list(flatten(children))
@@ -185,7 +175,7 @@ class STLVisitor(NodeVisitor):
         return Number(1) if node.text == "+" else Number(-1)
 
     def visit_AP(self, *args):
-        return ast.AtomicPred(*self.visit_var(*args))
+        return ast.AtomicPred(self.visit_id(*args))
 
     def visit_neg(self, _, children):
         return ast.Neg(children[1])
diff --git a/stl/test_parser.py b/stl/test_parser.py
index 379cd36..92de3b8 100644
--- a/stl/test_parser.py
+++ b/stl/test_parser.py
@@ -12,7 +12,7 @@ GRAMMAR = {
 }
 
 
-@given(ContextFreeGrammarStrategy(GRAMMAR, length=20, start='phi'))
+@given(ContextFreeGrammarStrategy(GRAMMAR, length=15, start='phi'))
 def test_invertable_repr(foo):
     note(''.join(foo))
     phi = stl.parse(''.join(foo))