diff --git a/slither/slithir/variables/constant.py b/slither/slithir/variables/constant.py
index 52cabf701..5da2d9cc0 100644
--- a/slither/slithir/variables/constant.py
+++ b/slither/slithir/variables/constant.py
@@ -1,4 +1,3 @@
-from fractions import Fraction
 from functools import total_ordering
 
 from slither.core.solidity_types.elementary_type import ElementaryType, Int, Uint
@@ -33,7 +32,7 @@ class Constant(SlithIRVariable):
         else:
             if val.isdigit():
                 self._type = ElementaryType("uint256")
-                self._val = int(Fraction(val))
+                self._val = convert_string_to_int(val)
             else:
                 self._type = ElementaryType("string")
                 self._val = val
diff --git a/slither/utils/arithmetic.py b/slither/utils/arithmetic.py
index 69684d103..d14958541 100644
--- a/slither/utils/arithmetic.py
+++ b/slither/utils/arithmetic.py
@@ -1,38 +1,35 @@
 from fractions import Fraction
 
 from slither.exceptions import SlitherException
+from slither.utils.integer_conversion import convert_string_to_int
 
 # pylint: disable=too-many-branches
 def convert_subdenomination(
     value: str, sub: str
 ) -> int:  # pylint: disable=too-many-return-statements
 
-    # to allow 0.1 ether conversion
-    if value[0:2] == "0x":
-        decimal_value = Fraction(int(value, 16))
-    else:
-        decimal_value = Fraction(value)
+    decimal_value = convert_string_to_int(value)
     if sub == "wei":
-        return int(decimal_value)
+        return decimal_value
     if sub == "gwei":
-        return int(decimal_value * int(1e9))
+        return decimal_value * 1e9
     if sub == "szabo":
-        return int(decimal_value * int(1e12))
+        return decimal_value * 1e12
     if sub == "finney":
-        return int(decimal_value * int(1e15))
+        return decimal_value * 1e15
     if sub == "ether":
-        return int(decimal_value * int(1e18))
+        return decimal_value * 1e18
     if sub == "seconds":
-        return int(decimal_value)
+        return decimal_value
     if sub == "minutes":
-        return int(decimal_value * 60)
+        return decimal_value * 60
     if sub == "hours":
-        return int(decimal_value * 60 * 60)
+        return decimal_value * 60 * 60
     if sub == "days":
-        return int(decimal_value * 60 * 60 * 24)
+        return decimal_value * 60 * 60 * 24
     if sub == "weeks":
-        return int(decimal_value * 60 * 60 * 24 * 7)
+        return decimal_value * 60 * 60 * 24 * 7
     if sub == "years":
-        return int(decimal_value * 60 * 60 * 24 * 7 * 365)
+        return decimal_value * 60 * 60 * 24 * 7 * 365
 
     raise SlitherException(f"Subdemonination conversion impossible {decimal_value} {sub}")
diff --git a/slither/utils/integer_conversion.py b/slither/utils/integer_conversion.py
index a410a956b..b7e2e98ff 100644
--- a/slither/utils/integer_conversion.py
+++ b/slither/utils/integer_conversion.py
@@ -4,11 +4,14 @@ from typing import Union
 from slither.exceptions import SlitherError
 
 
-def convert_string_to_int(val: Union[str, int]) -> int:
+def convert_string_to_fraction(val: Union[str, int]) -> Fraction:
     if isinstance(val, int):
-        return val
+        return Fraction(val)
     if val.startswith(("0x", "0X")):
-        return int(val, 16)
+        return Fraction(int(val, 16))
+
+    # Fractions do not support underscore separators (on Python <3.11)
+    val = val.replace('_', '')
 
     if "e" in val or "E" in val:
         base, expo = val.split("e") if "e" in val else val.split("E")
@@ -23,6 +26,9 @@ def convert_string_to_int(val: Union[str, int]) -> int:
                     f"{base}e{expo} is too large to fit in any Solidity integer size"
                 )
             return 0
-        return int(Fraction(base) * Fraction(10**expo))
+        return Fraction(base) * Fraction(10**expo)
 
-    return int(Fraction(val))
+    return Fraction(val)
+
+def convert_string_to_int(val: Union[str, int]) -> int:
+    return int(convert_string_to_fraction(val))
diff --git a/slither/visitors/expression/constants_folding.py b/slither/visitors/expression/constants_folding.py
index 2da1d7304..34ab34ffd 100644
--- a/slither/visitors/expression/constants_folding.py
+++ b/slither/visitors/expression/constants_folding.py
@@ -1,6 +1,5 @@
-from fractions import Fraction
 from slither.core.expressions import BinaryOperationType, Literal, UnaryOperationType
-from slither.utils.integer_conversion import convert_string_to_int
+from slither.utils.integer_conversion import convert_string_to_fraction, convert_string_to_int
 from slither.visitors.expression.expression import ExpressionVisitor
 
 
@@ -73,13 +72,13 @@ class ConstantFolding(ExpressionVisitor):
                 cf = ConstantFolding(expr, self._type)
                 expr = cf.result()
             assert isinstance(expr, Literal)
-            set_val(expression, int(expr.value))
+            set_val(expression, -convert_string_to_fraction(expr.value))
         else:
             raise NotConstant
 
     def _post_literal(self, expression):
         try:
-            set_val(expression, Fraction(expression.value))
+            set_val(expression, convert_string_to_fraction(expression.value))
         except ValueError:
             raise NotConstant
 
@@ -116,7 +115,7 @@ class ConstantFolding(ExpressionVisitor):
                 cf = ConstantFolding(expression.expressions[0], self._type)
                 expr = cf.result()
                 assert isinstance(expr, Literal)
-                set_val(expression, int(expr.value))
+                set_val(expression, convert_string_to_fraction(expr.value))
                 return
         raise NotConstant