diff --git a/mira/metamodel/utils.py b/mira/metamodel/utils.py
index 9b3df9968..e77732fb3 100644
--- a/mira/metamodel/utils.py
+++ b/mira/metamodel/utils.py
@@ -8,15 +8,22 @@
 
 def get_parseable_expression(s: str) -> str:
     """Return an expression that can be parsed using sympy."""
+    # Handle lambda which cannot be parsed by sympy
     s = s.replace('lambda', 'XXlambdaXX')
+    # Handle dots which also cannot be parsed
     s = re.sub(r'\.(?=\D)', 'XX_XX', s)
+    # Handle curly braces which are not allowed in sympy
+    s = s.replace('{', 'XXCBO').replace('}', 'XXCBC')
     s = unicodedata.normalize('NFKC', s)
     return s
 
 
 def revert_parseable_expression(s: str) -> str:
     """Return an expression to its original form."""
-    return s.replace('XXlambdaXX', 'lambda').replace("XX_XX", ".")
+    s = s.replace('XXCBO', '{').replace('XXCBC', '}')
+    s = s.replace('XX_XX', '.')
+    s = s.replace('XXlambdaXX', 'lambda')
+    return s
 
 
 def safe_parse_expr(s: str, local_dict=None) -> sympy.Expr:
diff --git a/tests/test_metamodel.py b/tests/test_metamodel.py
index de9af67a3..6fd3f46f4 100644
--- a/tests/test_metamodel.py
+++ b/tests/test_metamodel.py
@@ -240,7 +240,13 @@ def test_from_askenet_petri_mathml():
     assert mathml_str == org_str
 
 
-def test_safe_parse():
+def test_safe_parse_nfkc():
     eps = 'ϵ'
     eps_sym = sympy.Symbol(eps)
     assert safe_parse_expr(eps, local_dict={eps: eps_sym}) == eps_sym
+
+
+def test_safe_parse_curly_braces():
+    var = 'x_{a}'
+    var_sym = sympy.Symbol('x_{a}')
+    assert safe_parse_expr(var, local_dict={var: var_sym}) == var_sym
\ No newline at end of file