diff --git a/core/includes/common.inc b/core/includes/common.inc
index cf383c2..3da7fc0 100644
--- a/core/includes/common.inc
+++ b/core/includes/common.inc
@@ -1162,18 +1162,15 @@ function valid_url($url, $absolute = FALSE) {
 function valid_number_step($value, $step, $offset = 0.0) {
   $double_value = (double) abs($value - $offset);
 
-  // The precision length. Floating point numbers have limited precision.
-  // Although it depends on the system, PHP typically uses the IEEE 754 double
-  // precision format, which will give a maximum relative error due to rounding
-  // in the order of 1.11e-16.
-  $digits = 16;
+  // The number of digits a float has.
+  $digits = 24;
 
-  // This is max workable length for 32bit representation of mantissa.
-  $mantissa = 30;
+  // The number of digits a double has.
+  $mantissa = 53;
 
   // Double's fractional part size is $mantissa-bit. If the current value
-  // is greater than step*2^$mantissa, the following computation for
-  // remainder makes no sense.
+  // is greater than step*2^$mantissa, the following computation for remainder
+  // makes no sense.
   if ($double_value / pow(2.0, $mantissa) > $step) {
     return TRUE;
   }
@@ -1182,11 +1179,10 @@ function valid_number_step($value, $step, $offset = 0.0) {
   // ... that number subtracted from the step base is not an integral multiple
   // of the allowed value step, the element is suffering from a step mismatch.
   $remainder = (double) abs($double_value - $step * round($double_value / $step));
-  // Accepts erros in lower fractional part which IEEE 754 single-precision
-  // can't represent.
+  // Accepts erros in lower fractional part.
   $computed_acceptable_error = (double)($step / pow(2.0, $mantissa));
 
-  return !($computed_acceptable_error < $remainder && $remainder < ($step - $computed_acceptable_error));
+  return $computed_acceptable_error >= $remainder && $remainder >= ($step - $computed_acceptable_error);
 }
 
 /**