diff --git a/ext/standard/math.c b/ext/standard/math.c
index 74ffa565031a3..46a777e16399f 100644
--- a/ext/standard/math.c
+++ b/ext/standard/math.c
@@ -99,7 +99,8 @@ static inline double php_round_helper(double value, int mode) {
 		tmp_value = floor(value + 0.5);
 		if ((mode == PHP_ROUND_HALF_DOWN && value == (-0.5 + tmp_value)) ||
 			(mode == PHP_ROUND_HALF_EVEN && value == (0.5 + 2 * floor(tmp_value/2.0))) ||
-			(mode == PHP_ROUND_HALF_ODD  && value == (0.5 + 2 * floor(tmp_value/2.0) - 1.0)))
+			(mode == PHP_ROUND_HALF_ODD  && value == (0.5 + 2 * floor(tmp_value/2.0) - 1.0)) ||
+			value < (-0.5 + tmp_value))
 		{
 			tmp_value = tmp_value - 1.0;
 		}
@@ -107,7 +108,8 @@ static inline double php_round_helper(double value, int mode) {
 		tmp_value = ceil(value - 0.5);
 		if ((mode == PHP_ROUND_HALF_DOWN && value == (0.5 + tmp_value)) ||
 			(mode == PHP_ROUND_HALF_EVEN && value == (-0.5 + 2 * ceil(tmp_value/2.0))) ||
-			(mode == PHP_ROUND_HALF_ODD  && value == (-0.5 + 2 * ceil(tmp_value/2.0) + 1.0)))
+			(mode == PHP_ROUND_HALF_ODD  && value == (-0.5 + 2 * ceil(tmp_value/2.0) + 1.0)) ||
+			value > (0.5 + tmp_value))
 		{
 			tmp_value = tmp_value + 1.0;
 		}
@@ -131,7 +133,7 @@ PHPAPI double _php_math_round(double value, int places, int mode) {
 		return value;
 	}
 
-	places = places < INT_MIN+1 ? INT_MIN+1 : places;
+	places = places < INT_MIN + 1 ? INT_MIN + 1 : places;
 	precision_places = 14 - php_intlog10abs(value);
 
 	f1 = php_intpow10(abs(places));
@@ -140,7 +142,7 @@ PHPAPI double _php_math_round(double value, int places, int mode) {
 	   the requested places BUT is small enough to make sure a non-zero value
 	   is returned, pre-round the result to the precision */
 	if (precision_places > places && precision_places - 15 < places) {
-		int64_t use_precision = precision_places < INT_MIN+1 ? INT_MIN+1 : precision_places;
+		int64_t use_precision = precision_places < INT_MIN + 1 ? INT_MIN + 1 : precision_places;
 
 		f2 = php_intpow10(abs((int)use_precision));
 		if (use_precision >= 0) {
@@ -153,7 +155,7 @@ PHPAPI double _php_math_round(double value, int places, int mode) {
 		tmp_value = php_round_helper(tmp_value, mode);
 
 		use_precision = places - precision_places;
-		use_precision = use_precision < INT_MIN+1 ? INT_MIN+1 : use_precision;
+		use_precision = use_precision < INT_MIN + 1 ? INT_MIN + 1 : use_precision;
 		/* now correctly move the decimal point */
 		f2 = php_intpow10(abs((int)use_precision));
 		/* because places < precision_places */
diff --git a/ext/standard/tests/math/round_bug12143.phpt b/ext/standard/tests/math/round_bug12143.phpt
new file mode 100644
index 0000000000000..25797a36100e9
--- /dev/null
+++ b/ext/standard/tests/math/round_bug12143.phpt
@@ -0,0 +1,38 @@
+--TEST--
+Bug #12143 round() with large FP
+--FILE--
+<?php
+var_dump(round(0.49999999999999994, 0, PHP_ROUND_HALF_UP));
+var_dump(round(0.49999999999999994, 0, PHP_ROUND_HALF_DOWN));
+var_dump(round(0.49999999999999994, 0, PHP_ROUND_HALF_EVEN));
+var_dump(round(0.49999999999999994, 0, PHP_ROUND_HALF_ODD));
+var_dump(round(-0.49999999999999994, 0, PHP_ROUND_HALF_UP));
+var_dump(round(-0.49999999999999994, 0, PHP_ROUND_HALF_DOWN));
+var_dump(round(-0.49999999999999994, 0, PHP_ROUND_HALF_EVEN));
+var_dump(round(-0.49999999999999994, 0, PHP_ROUND_HALF_ODD));
+var_dump(round(0.5000000000000004, 0, PHP_ROUND_HALF_UP));
+var_dump(round(0.5000000000000004, 0, PHP_ROUND_HALF_DOWN));
+var_dump(round(0.5000000000000004, 0, PHP_ROUND_HALF_EVEN));
+var_dump(round(0.5000000000000004, 0, PHP_ROUND_HALF_ODD));
+var_dump(round(-0.5000000000000004, 0, PHP_ROUND_HALF_UP));
+var_dump(round(-0.5000000000000004, 0, PHP_ROUND_HALF_DOWN));
+var_dump(round(-0.5000000000000004, 0, PHP_ROUND_HALF_EVEN));
+var_dump(round(-0.5000000000000004, 0, PHP_ROUND_HALF_ODD));
+?>
+--EXPECT--
+float(0)
+float(0)
+float(0)
+float(0)
+float(0)
+float(0)
+float(0)
+float(0)
+float(1)
+float(1)
+float(1)
+float(1)
+float(-1)
+float(-1)
+float(-1)
+float(-1)