diff --git a/ext/standard/math.c b/ext/standard/math.c
index b8c713d4208..7163bfa9c56 100644
--- a/ext/standard/math.c
+++ b/ext/standard/math.c
@@ -1020,7 +1020,12 @@ PHPAPI char *_php_math_number_format(double d, int dec, char dec_point, char tho
 		is_negative = 1;
 		d = -d;
 	}
-	dec = MAX(0, dec);
+	if (!dec_point && dec > 0) {
+		d *= pow(10, dec);
+		dec = 0;
+	} else {
+		dec = MAX(0, dec);
+	}
 
 	PHP_ROUND_WITH_FUZZ(d, dec);
 
@@ -1140,6 +1145,8 @@ PHP_FUNCTION(number_format)
 		convert_to_string_ex(t_s);
 		if (Z_STRLEN_PP(d_p)==1) {
 			dec_point=Z_STRVAL_PP(d_p)[0];
+		} else if (Z_STRLEN_PP(d_p)==0) {
+			dec_point=0;
 		}
 		if (Z_STRLEN_PP(t_s)==1) {
 			thousand_sep=Z_STRVAL_PP(t_s)[0];
diff --git a/ext/standard/tests/math/bug28228.phpt b/ext/standard/tests/math/bug28228.phpt
new file mode 100755
index 00000000000..3d6cebcfd42
--- /dev/null
+++ b/ext/standard/tests/math/bug28228.phpt
@@ -0,0 +1,14 @@
+--TEST--
+Bug #28228 (number_format() does not allow empty decimal separator)
+--FILE--
+<?php
+echo number_format(1234.5678, 4, '', '') . "\n";
+echo number_format(1234.5678, 4, NULL, ',') . "\n";
+echo number_format(1234.5678, 4, 0, ',') . "\n";
+echo number_format(1234.5678, 4);
+?>
+--EXPECT--
+12345678
+12,345,678
+1,23405678
+1,234.5678