Index: wp-includes/functions.php
===================================================================
--- wp-includes/functions.php	(revision 12317)
+++ wp-includes/functions.php	(working copy)
@@ -140,6 +140,10 @@
 	// let the user override the precision only
 	$decimals = ( is_null( $decimals ) ) ? $wp_locale->number_format['decimals'] : intval( $decimals );
 
+	// if the number is not floating point number set the number of decimals to zero
+	if ( !is_float( $number ) )
+		$decimals = 0;
+
 	$num = number_format( $number, $decimals, $wp_locale->number_format['decimal_point'], $wp_locale->number_format['thousands_sep'] );
 
 	// let the user translate digits from latin to localized language