diff --git a/lib/pure/rationals.nim b/lib/pure/rationals.nim
index 3443f75d4c..7fb24c26f3 100644
--- a/lib/pure/rationals.nim
+++ b/lib/pure/rationals.nim
@@ -39,7 +39,7 @@ proc toRational*[T:SomeInteger](x: T): Rational[T] =
   result.num = x
   result.den = 1
 
-proc toRational*(x: float, n: int = high(int)): Rational[int] =
+proc toRational*(x: float, n: int = high(int32)): Rational[int] =
   ## Calculates the best rational numerator and denominator
   ## that approximates to `x`, where the denominator is
   ## smaller than `n` (default is the largest possible
@@ -60,19 +60,17 @@ proc toRational*(x: float, n: int = high(int)): Rational[int] =
   var
     m11, m22 = 1
     m12, m21 = 0
-    ai = x.int
+    ai = int(x)
     x = x
-  while m21.float * ai.float + m22.float <= n.float:
+  while m21 * ai + m22 <= n:
     swap m12, m11
     swap m22, m21
     m11 = m12 * ai + m11
     m21 = m22 * ai + m21
-    if x == ai.float: # division by zero
-      break
-    if x > 0x7FFFFFFF.float: # representation failure
-      break
-    x = 1.0 / (x - ai.float)
-    ai = x.int
+    if x == float(ai): break  # division by zero
+    x = 1/(x - float(ai))
+    if x > float(high(int32)): break  # representation failure
+    ai = int(x)
   result = m11 // m21
 
 proc toFloat*[T](x: Rational[T]): float =
@@ -325,15 +323,14 @@ when isMainModule:
   assert abs(toFloat(y) - 0.4814814814814815) < 1.0e-7
   assert toInt(z) == 0
 
-  assert $toRational(0.98765432) == "5376864444397469455/5444075255396513284"
-  assert $toRational(PI) == "8566508067901016491/2726804208086097199"
-  assert toRational(0.1, 1000000) == 1 // 10
-  assert toRational(0.9, 1000000) == 9 // 10
-  #assert toRational(PI) == 80143857 // 25510582
+  assert toRational(0.98765432) == 2111111029 // 2137499919
+  assert toRational(PI) == 817696623 // 260280919
+  assert toRational(0.1) == 1 // 10
+  assert toRational(0.9) == 9 // 10
 
   assert toRational(0.0) == 0 // 1
-  assert toRational(-0.25, 10) == 1 // -4
-  assert toRational(3.2, 10) == 16 // 5
-  assert toRational(0.33, 100) == 33 // 100
-  assert toRational(0.22, 50) == 11 // 50
+  assert toRational(-0.25) == 1 // -4
+  assert toRational(3.2) == 16 // 5
+  assert toRational(0.33) == 33 // 100
+  assert toRational(0.22) == 11 // 50
   assert toRational(10.0) == 10 // 1