diff --git a/php_decimal.c b/php_decimal.c
index cbcb9c3..e297ec5 100644
--- a/php_decimal.c
+++ b/php_decimal.c
@@ -592,6 +592,17 @@ static void php_decimal_set_nan(php_decimal_t *obj)
     php_decimal_mpd_set_nan(PHP_DECIMAL_MPD(obj));
 }
 
+/**
+ * Sets the value to "0" in case it is "-0"
+ */
+static void php_decimal_prevent_negative_zero(mpd_t *mpd)
+{
+    if (mpd_iszero(mpd) && mpd_isnegative(mpd)) {
+        uint32_t status = 0;
+        mpd_qcopy_negate(mpd, mpd, &status);
+    }
+}
+
 /**
  * Parses a string to a given precision. Trailing zeroes are not preserved.
  */
@@ -617,6 +628,8 @@ static php_success_t php_decimal_mpd_set_string(mpd_t *mpd, zend_string *str, ze
         php_decimal_loss_of_data_on_string_conversion();
     }
 
+    php_decimal_prevent_negative_zero(mpd);
+
     return SUCCESS;
 }
 
@@ -1157,12 +1170,16 @@ static void php_decimal_ceil(php_decimal_t *res, mpd_t *op1)
  */
 static void php_decimal_truncate(php_decimal_t *res, mpd_t *op1)
 {
+    mpd_t *mpd = PHP_DECIMAL_MPD(res);
     uint32_t status = 0;
+
     if (mpd_isspecial(op1)) {
-        mpd_qcopy(PHP_DECIMAL_MPD(res), op1, &status);
+        mpd_qcopy(mpd, op1, &status);
         return;
     }
-    mpd_qtrunc(PHP_DECIMAL_MPD(res), op1, php_decimal_context(), &status);
+
+    mpd_qtrunc(mpd, op1, php_decimal_context(), &status);
+    php_decimal_prevent_negative_zero(mpd);
 }
 
 /**
@@ -1197,6 +1214,12 @@ static void php_decimal_abs(php_decimal_t *res, mpd_t *op1)
 static void php_decimal_negate(php_decimal_t *res, mpd_t *op1)
 {
     uint32_t status = 0;
+
+    if (mpd_iszero(op1)) {
+        mpd_qcopy(PHP_DECIMAL_MPD(res), op1, &status);
+        return;
+    }
+
     mpd_qcopy_negate(PHP_DECIMAL_MPD(res), op1, &status);
 }
 
@@ -1433,6 +1456,8 @@ static void php_decimal_do_binary_op(php_decimal_binary_op_t op, php_decimal_t *
     php_decimal_set_precision(res, prec);
     op(res, mpd1, mpd2);
     mpd_del(&tmp);
+
+    php_decimal_prevent_negative_zero(PHP_DECIMAL_MPD(res));
 }
 
 
@@ -2201,7 +2226,10 @@ PHP_DECIMAL_METHOD(round)
         #endif
     ZEND_PARSE_PARAMETERS_END();
 
-    php_decimal_round_mpd(PHP_DECIMAL_MPD(res), PHP_DECIMAL_MPD(obj), places, rounding);
+    mpd_t *mpd = PHP_DECIMAL_MPD(res);
+    php_decimal_round_mpd(mpd, PHP_DECIMAL_MPD(obj), places, rounding);
+    php_decimal_prevent_negative_zero(mpd);
+
     RETURN_DECIMAL(res);
 }
 
@@ -2376,7 +2404,7 @@ PHP_DECIMAL_METHOD(isPositive)
 
     mpd_t *mpd = THIS_MPD();
 
-    RETURN_BOOL(!mpd_isnan(mpd) && mpd_ispositive(mpd));
+    RETURN_BOOL(!mpd_isnan(mpd) && !mpd_iszero(mpd) && mpd_ispositive(mpd));
 }
 
 /**
@@ -2390,7 +2418,7 @@ PHP_DECIMAL_METHOD(isNegative)
 
     mpd_t *mpd = THIS_MPD();
 
-    RETURN_BOOL(!mpd_isnan(mpd) && mpd_isnegative(mpd));
+    RETURN_BOOL(!mpd_isnan(mpd) && !mpd_iszero(mpd) && mpd_isnegative(mpd));
 }
 
 /**
diff --git a/tests/php7/cast.phpt b/tests/php7/cast.phpt
index bb42d28..79e6986 100644
--- a/tests/php7/cast.phpt
+++ b/tests/php7/cast.phpt
@@ -19,7 +19,7 @@ $tests = [
      * STRING
      */
     [(string) decimal(),                "0"],
-    [(string) decimal("-0"),           "-0"],
+    [(string) decimal("-0"),            "0"],
     [(string) decimal("5.2"),           "5.2"],
 
     [(string) decimal( "NAN"),          "NAN"],
diff --git a/tests/php7/clone.phpt b/tests/php7/clone.phpt
index 43ec8e9..eaa85e1 100644
--- a/tests/php7/clone.phpt
+++ b/tests/php7/clone.phpt
@@ -11,6 +11,12 @@ use Decimal\Decimal;
 $a = new Decimal("1.234", 16);
 $b = clone $a;
 
+var_dump($a);
+var_dump($b);
+
+$a = new Decimal("-0");
+$b = clone $a;
+
 var_dump($a);
 var_dump($b);
 ?>
@@ -27,3 +33,15 @@ object(Decimal\Decimal)#2 (2) {
   ["precision"]=>
   int(16)
 }
+object(Decimal\Decimal)#3 (2) {
+  ["value"]=>
+  string(1) "0"
+  ["precision"]=>
+  int(28)
+}
+object(Decimal\Decimal)#1 (2) {
+  ["value"]=>
+  string(1) "0"
+  ["precision"]=>
+  int(28)
+}
diff --git a/tests/php7/empty.phpt b/tests/php7/empty.phpt
index e5a94fc..5d41d9d 100644
--- a/tests/php7/empty.phpt
+++ b/tests/php7/empty.phpt
@@ -10,6 +10,7 @@ use Decimal\Decimal;
 
 var_dump(empty(new Decimal()));
 var_dump(empty(new Decimal(0)));
+var_dump(empty(new Decimal('-0')));
 var_dump(empty(new Decimal(1)));
 
 var_dump(empty(new Decimal( "1E-1000")));
@@ -28,3 +29,4 @@ bool(false)
 bool(false)
 bool(false)
 bool(false)
+bool(false)
diff --git a/tests/php7/json.phpt b/tests/php7/json.phpt
index d570c72..0e11610 100644
--- a/tests/php7/json.phpt
+++ b/tests/php7/json.phpt
@@ -9,9 +9,11 @@ if (!extension_loaded("json"))    echo 'skip';
 <?php
 use Decimal\Decimal;
 
+var_dump(json_encode(new Decimal("-0", 20)));
 var_dump(json_encode(new Decimal("1.2345", 20)));
 var_dump(json_encode(new Decimal("5.0000", 20)));
 ?>
 --EXPECT--
+string(3) ""0""
 string(8) ""1.2345""
 string(8) ""5.0000""
diff --git a/tests/php7/methods/abs.phpt b/tests/php7/methods/abs.phpt
index 8a7fe76..4948f45 100644
--- a/tests/php7/methods/abs.phpt
+++ b/tests/php7/methods/abs.phpt
@@ -14,6 +14,9 @@ use Decimal\Decimal;
 function decimal(...$args) { return new Decimal(...$args); }
 
 $tests = [
+    ["0", "0"],
+    ["-0", "0"],
+
     ["-0.1", "0.1"],
     ["+0.1", "0.1"],
     [ "0.1", "0.1"],
diff --git a/tests/php7/methods/avg.phpt b/tests/php7/methods/avg.phpt
index 41f390f..74f22c0 100644
--- a/tests/php7/methods/avg.phpt
+++ b/tests/php7/methods/avg.phpt
@@ -39,6 +39,9 @@ $tests = [
     [[array('-2.3', '4.1', 5),   ], "2.266666666666666666666666667",   28],
     [[array('-2.3', '4.1', 5), 10], "2.266666667",                     10],
     [[array('-2.3', '4.1', 5), 30], "2.26666666666666666666666666667", 30],
+
+    [[[decimal("0.1"), decimal("-0.1")]], "0.0", 28],
+    [[[decimal("-0.1"), decimal("0.1")]], "0.0", 28],
 ];
 
 foreach ($tests as $index => $test) {
diff --git a/tests/php7/methods/ceil.phpt b/tests/php7/methods/ceil.phpt
index b932162..4b0d082 100644
--- a/tests/php7/methods/ceil.phpt
+++ b/tests/php7/methods/ceil.phpt
@@ -14,6 +14,9 @@ use Decimal\Decimal;
 function decimal(...$args) { return new Decimal(...$args); }
 
 $tests = [
+    ["0",          "0"],
+    ["-0",         "0"],
+
     ["-0.1",       "-0"],
     [ "0.1",        "1"],
 
diff --git a/tests/php7/methods/compareTo.phpt b/tests/php7/methods/compareTo.phpt
index f1da14a..0e3cbff 100644
--- a/tests/php7/methods/compareTo.phpt
+++ b/tests/php7/methods/compareTo.phpt
@@ -29,6 +29,11 @@ $tests = [
     [decimal(),     false,  1],
     [decimal(),     0.0,    0],
 
+    [decimal("-0"), 0,      0],
+    [decimal("-0"), null,   1],
+    [decimal("-0"), false,  1],
+    [decimal("-0"), 0.0,    0],
+
     [decimal(1),    0,      1],
     [decimal(1),    null,   1],
     [decimal(1),    false,  1],
diff --git a/tests/php7/methods/copy.phpt b/tests/php7/methods/copy.phpt
index e7322c0..0156a63 100644
--- a/tests/php7/methods/copy.phpt
+++ b/tests/php7/methods/copy.phpt
@@ -11,6 +11,11 @@ $dst = $src->copy();
 
 var_dump($src, $dst);
 
+$src = new Decimal\Decimal("-0", 32);
+$dst = $src->copy();
+
+var_dump($src, $dst);
+
 ?>
 --EXPECT--
 object(Decimal\Decimal)#1 (2) {
@@ -25,3 +30,15 @@ object(Decimal\Decimal)#2 (2) {
   ["precision"]=>
   int(32)
 }
+object(Decimal\Decimal)#3 (2) {
+  ["value"]=>
+  string(1) "0"
+  ["precision"]=>
+  int(32)
+}
+object(Decimal\Decimal)#1 (2) {
+  ["value"]=>
+  string(1) "0"
+  ["precision"]=>
+  int(32)
+}
diff --git a/tests/php7/methods/div.phpt b/tests/php7/methods/div.phpt
index 748922d..40787c4 100644
--- a/tests/php7/methods/div.phpt
+++ b/tests/php7/methods/div.phpt
@@ -65,6 +65,17 @@ $tests = [
     [new Decimal("-INF"),  "NAN", (string) (-INF /  NAN), 28],
     [new Decimal("-INF"),  "INF", (string) (-INF /  INF), 28],
     [new Decimal("-INF"), "-INF", (string) (-INF / -INF), 28],
+
+    [
+        new Decimal("0"),
+        new Decimal("10"),
+                    "0",    28
+    ],
+    [
+        new Decimal("-0"),
+        new Decimal("10"),
+                    "0",    28
+    ],
 ];
 
 foreach ($tests as $index => $test) {
diff --git a/tests/php7/methods/equals.phpt b/tests/php7/methods/equals.phpt
index 03d82cc..aec7c24 100644
--- a/tests/php7/methods/equals.phpt
+++ b/tests/php7/methods/equals.phpt
@@ -36,6 +36,8 @@ $tests = [
     [decimal(1), 1.0,    true],
     [decimal(1), "1",    true],
 
+    [decimal("-0"), 0,    true],
+
     [decimal("0.1"),        0.1,    true],
     [decimal("0.2"),        0.2,    true],
     [decimal("0.200"),      0.2,    true],
diff --git a/tests/php7/methods/exp.phpt b/tests/php7/methods/exp.phpt
index 53d8f6e..e2c8e4a 100644
--- a/tests/php7/methods/exp.phpt
+++ b/tests/php7/methods/exp.phpt
@@ -14,6 +14,9 @@ use Decimal\Decimal;
 function decimal(...$args) { return new Decimal(...$args); }
 
 $tests = [
+    [decimal("0"),  "1", 28],
+    [decimal("-0"), "1", 28],
+
     [decimal("-0.1", 50), "0.90483741803595957316424905944643662119470536098040", 50],
     [decimal( "0.1", 50), "1.1051709180756476248117078264902466682245471947375", 50],
 
diff --git a/tests/php7/methods/floor.phpt b/tests/php7/methods/floor.phpt
index 1156032..392d047 100644
--- a/tests/php7/methods/floor.phpt
+++ b/tests/php7/methods/floor.phpt
@@ -14,6 +14,9 @@ use Decimal\Decimal;
 function decimal(...$args) { return new Decimal(...$args); }
 
 $tests = [
+    ["0",          "0"],
+    ["-0",         "0"],
+
     ["-0.1",       "-1"],
     [ "0.1",        "0"],
 
diff --git a/tests/php7/methods/isEven.phpt b/tests/php7/methods/isEven.phpt
index 3bddc8f..be2bb17 100644
--- a/tests/php7/methods/isEven.phpt
+++ b/tests/php7/methods/isEven.phpt
@@ -20,6 +20,7 @@ $tests = [
     ["-2.000000000000000000000000001",   false], // not truncated
 
     [0,         true],
+    ["-0",      true],
     [1,         false],
     [2,         true],
     [3,         false],
diff --git a/tests/php7/methods/isInf.phpt b/tests/php7/methods/isInf.phpt
index 4a58d06..c7f037f 100644
--- a/tests/php7/methods/isInf.phpt
+++ b/tests/php7/methods/isInf.phpt
@@ -20,6 +20,7 @@ $tests = [
     ["-1E-50",  false],
 
     [0,         false],
+    ["-0",      false],
     [1,         false],
     [2,         false],
     [3,         false],
diff --git a/tests/php7/methods/isInteger.phpt b/tests/php7/methods/isInteger.phpt
index 93e713f..cc432c2 100644
--- a/tests/php7/methods/isInteger.phpt
+++ b/tests/php7/methods/isInteger.phpt
@@ -20,6 +20,7 @@ $tests = [
     ["-1E-50",  false],
 
     [0,         true],
+    ["-0",      true],
     [1,         true],
     [2,         true],
     [3,         true],
diff --git a/tests/php7/methods/isNaN.phpt b/tests/php7/methods/isNaN.phpt
index 82c3967..6be6a7c 100644
--- a/tests/php7/methods/isNaN.phpt
+++ b/tests/php7/methods/isNaN.phpt
@@ -20,6 +20,7 @@ $tests = [
     ["-1E-50",  false],
 
     [0,         false],
+    ["-0",      false],
     [1,         false],
     [2,         false],
     [3,         false],
diff --git a/tests/php7/methods/isNegative.phpt b/tests/php7/methods/isNegative.phpt
index b181342..cb55de1 100644
--- a/tests/php7/methods/isNegative.phpt
+++ b/tests/php7/methods/isNegative.phpt
@@ -20,7 +20,7 @@ $tests = [
     ["-1E-50",  true],
 
     ["0",       false],
-    ["-0",      true],
+    ["-0",      false],
     [1,         false],
     [2,         false],
     [3,         false],
diff --git a/tests/php7/methods/isOdd.phpt b/tests/php7/methods/isOdd.phpt
index f64093c..0068d93 100644
--- a/tests/php7/methods/isOdd.phpt
+++ b/tests/php7/methods/isOdd.phpt
@@ -20,6 +20,7 @@ $tests = [
     ["-3.000000000000000000000000001",   false], // not truncated
 
     [0,         false],
+    ["-0",      false],
     [1,         true],
     [2,         false],
     [3,         true],
diff --git a/tests/php7/methods/isPositive.phpt b/tests/php7/methods/isPositive.phpt
index 96e0fc2..6a968d7 100644
--- a/tests/php7/methods/isPositive.phpt
+++ b/tests/php7/methods/isPositive.phpt
@@ -19,7 +19,7 @@ $tests = [
     [ "1E-50",  true],
     ["-1E-50",  false],
 
-    ["0",       true],
+    ["0",       false],
     ["-0",      false],
     [1,         true],
     [2,         true],
diff --git a/tests/php7/methods/isZero.phpt b/tests/php7/methods/isZero.phpt
index d27abe4..370e87b 100644
--- a/tests/php7/methods/isZero.phpt
+++ b/tests/php7/methods/isZero.phpt
@@ -20,6 +20,7 @@ $tests = [
     ["-1E-50",  false],
 
     [0,         true],
+    ["-0",      true],
     [1,         false],
     [2,         false],
     [3,         false],
diff --git a/tests/php7/methods/ln.phpt b/tests/php7/methods/ln.phpt
index 29292a7..6ff1410 100644
--- a/tests/php7/methods/ln.phpt
+++ b/tests/php7/methods/ln.phpt
@@ -40,6 +40,7 @@ $tests = [
     [decimal( "NAN"), (string) log( NAN), 28],
     [decimal( "INF"), (string) log( INF), 28],
     [decimal(   "0"), (string) log(   0), 28],
+    [decimal(  "-0"), (string) log(   0), 28],
     [decimal(  "-1"), (string) log(  -1), 28],
 ];
 
diff --git a/tests/php7/methods/log10.phpt b/tests/php7/methods/log10.phpt
index c92bb22..8c4694c 100644
--- a/tests/php7/methods/log10.phpt
+++ b/tests/php7/methods/log10.phpt
@@ -40,6 +40,7 @@ $tests = [
     [decimal( "NAN"), (string) log10( NAN), 28],
     [decimal( "INF"), (string) log10( INF), 28],
     [decimal(   "0"), (string) log10(   0), 28],
+    [decimal(  "-0"), (string) log10(   0), 28],
     [decimal(  "-1"), (string) log10(  -1), 28],
 ];
 
diff --git a/tests/php7/methods/mod.phpt b/tests/php7/methods/mod.phpt
index 4866915..8734344 100644
--- a/tests/php7/methods/mod.phpt
+++ b/tests/php7/methods/mod.phpt
@@ -19,6 +19,8 @@ function decimal(...$args) { return new Decimal(...$args); }
 $tests = [
     [decimal("0"),        "1",    0 %  1,    28],
     [decimal("0"),       "-1",    0 % -1,    28],
+    [decimal("-0"),       "1",    0 %  1,    28],
+    [decimal("-0"),      "-1",    0 % -1,    28],
 
     [decimal( "1"),       "3",    1 %  3,    28],
     [decimal( "1"),      "-3",    1 % -3,    28],
diff --git a/tests/php7/methods/mul.phpt b/tests/php7/methods/mul.phpt
index 8577034..c2af5ee 100644
--- a/tests/php7/methods/mul.phpt
+++ b/tests/php7/methods/mul.phpt
@@ -75,6 +75,9 @@ $tests = [
     [new Decimal( "NAN"), 0, "NAN", 28],
     [new Decimal( "INF"), 0, "NAN", 28],
     [new Decimal("-INF"), 0, "NAN", 28],
+
+    [new Decimal("0"),  2, "0", 28],
+    [new Decimal("-0"), 2, "0", 28],
 ];
 
 foreach ($tests as $index => $test) {
@@ -122,8 +125,8 @@ Warning: Loss of data on string conversion in %s on line 24
 
 Warning: Loss of data on string conversion in %s on line 25
 
-Warning: Loss of data on integer conversion in %s on line 77
+Warning: Loss of data on integer conversion in %s on line 80
 
-Warning: Loss of data on integer conversion in %s on line 79
+Warning: Loss of data on integer conversion in %s on line 82
 
-Warning: Loss of data on integer conversion in %s on line 80
+Warning: Loss of data on integer conversion in %s on line 83
diff --git a/tests/php7/methods/negate.phpt b/tests/php7/methods/negate.phpt
index 0af2b21..e5c5f60 100644
--- a/tests/php7/methods/negate.phpt
+++ b/tests/php7/methods/negate.phpt
@@ -34,9 +34,9 @@ var_dump((string) $obj);
 
 ?>
 --EXPECT--
-string(2) "-0"
 string(1) "0"
-string(2) "-0"
+string(1) "0"
+string(1) "0"
 string(2) "-1"
 string(1) "1"
 string(3) "NAN"
diff --git a/tests/php7/methods/pow.phpt b/tests/php7/methods/pow.phpt
index 14d7ac9..7dba45b 100644
--- a/tests/php7/methods/pow.phpt
+++ b/tests/php7/methods/pow.phpt
@@ -23,6 +23,8 @@ $tests = [
 
     [decimal("0"),   "0",    pow(0, 0)],
     [decimal("0"),   "1",    pow(0, 1)],
+    [decimal("-0"),  "0",    pow(0, 0)],
+    [decimal("-0"),  "1",    pow(0, 1)],
 
     [decimal("1"),  "-2",    pow(1, -2)],
     [decimal("1"),  "-1",    pow(1, -1)],
diff --git a/tests/php7/methods/rem.phpt b/tests/php7/methods/rem.phpt
index 068ba63..7fab407 100644
--- a/tests/php7/methods/rem.phpt
+++ b/tests/php7/methods/rem.phpt
@@ -19,6 +19,8 @@ function decimal(...$args) { return new Decimal(...$args); }
 $tests = [
     [decimal("0"),        "1",    0 %  1,    28],
     [decimal("0"),       "-1",    0 % -1,    28],
+    [decimal("-0"),       "1",    0 %  1,    28],
+    [decimal("-0"),      "-1",    0 % -1,    28],
 
     [decimal( "1"),       "3",    1 %  3,    28],
     [decimal( "1"),      "-3",    1 % -3,    28],
diff --git a/tests/php7/methods/round.phpt b/tests/php7/methods/round.phpt
index 2164516..0045b4a 100644
--- a/tests/php7/methods/round.phpt
+++ b/tests/php7/methods/round.phpt
@@ -298,6 +298,10 @@ $tests = [
     ["123.45",  10, [Decimal::ROUND_HALF_UP], "123.45"],
     ["1234.5",  10, [Decimal::ROUND_HALF_UP], "1234.5"],
     ["12345",   10, [Decimal::ROUND_HALF_UP], "12345"],
+
+    /* NEGATIVE VALUE TO ZERO */
+    ["-0.1", 0, [Decimal::ROUND_HALF_UP], "0"],
+    ["-0.000001", 3, [Decimal::ROUND_HALF_UP], "0.000"],
 ];
 
 foreach ($tests as $test) {
diff --git a/tests/php7/methods/shift.phpt b/tests/php7/methods/shift.phpt
index 14c01ff..5e05429 100644
--- a/tests/php7/methods/shift.phpt
+++ b/tests/php7/methods/shift.phpt
@@ -16,6 +16,9 @@ function decimal(...$args) { return new Decimal(...$args); }
 $tests = [
     /* A * B = C */
 
+    ["0",       -3,      "0.000"],
+    ["-0",      -3,      "0.000"],
+
     ["1",       -3,      "0.001"],
     ["1",       -2,      "0.01"],
     ["1",       -1,      "0.1"],
diff --git a/tests/php7/methods/sqrt.phpt b/tests/php7/methods/sqrt.phpt
index 5e3a5a4..297930b 100644
--- a/tests/php7/methods/sqrt.phpt
+++ b/tests/php7/methods/sqrt.phpt
@@ -15,6 +15,9 @@ function decimal(...$args) { return new Decimal(...$args); }
 
 $tests = [
     [decimal(),             "0",                                                       28],
+    [decimal("0"),          "0",                                                       28],
+    [decimal("-0"),         "0",                                                       28],
+
     [decimal("0.1", 5),     "0.31623",                                                  5],
     [decimal("0.1"),        "0.3162277660168379331998893544",                          28],
     [decimal("0.1", 50),    "0.31622776601683793319988935444327185337195551393252",    50],
diff --git a/tests/php7/methods/sum.phpt b/tests/php7/methods/sum.phpt
index 28bea71..d28def1 100644
--- a/tests/php7/methods/sum.phpt
+++ b/tests/php7/methods/sum.phpt
@@ -39,6 +39,9 @@ $tests = [
     [[array('-2.3', '4.1'),   ], "1.8", 28],
     [[array('-2.3', '4.1'), 10], "1.8", 10],
     [[array('-2.3', '4.1'), 30], "1.8", 30],
+
+    [[[decimal("0.1"), decimal("-0.1")]], "0.0", 28],
+    [[[decimal("-0.1"), decimal("0.1")]], "0.0", 28],
 ];
 
 foreach ($tests as $index => $test) {
diff --git a/tests/php7/methods/toFixed.phpt b/tests/php7/methods/toFixed.phpt
index 9b1d6f9..baa8f87 100644
--- a/tests/php7/methods/toFixed.phpt
+++ b/tests/php7/methods/toFixed.phpt
@@ -12,6 +12,7 @@ $tests = [
     /* decimal places, grouped, rounding mode, expected */
 
     ["0",           5,     false,   Decimal::ROUND_HALF_UP,      "0.00000"],
+    ["-0",          5,     false,   Decimal::ROUND_HALF_UP,      "0.00000"],
 
     ["1.23456",     3,     false,   Decimal::ROUND_UP,           "1.235"],
     ["1.23456",     3,     false,   Decimal::ROUND_DOWN,         "1.234"],
diff --git a/tests/php7/methods/toFloat.phpt b/tests/php7/methods/toFloat.phpt
index 6661f17..90f9397 100644
--- a/tests/php7/methods/toFloat.phpt
+++ b/tests/php7/methods/toFloat.phpt
@@ -16,6 +16,7 @@ function decimal(...$args) { return new Decimal(...$args); }
 
 $tests = [
     ["0",        0.0],
+    ["-0",       0.0],
 
     ["-0.1",    -0.1],
     [ "0.1",     0.1],
diff --git a/tests/php7/methods/toInt.phpt b/tests/php7/methods/toInt.phpt
index bcf663a..45769c1 100644
--- a/tests/php7/methods/toInt.phpt
+++ b/tests/php7/methods/toInt.phpt
@@ -15,6 +15,7 @@ function decimal(...$args) { return new Decimal(...$args); }
 
 $tests = [
     ["0",  0],
+    ["-0", 0],
 
     ["-0.1",  0],
     [ "0.1",  0],
diff --git a/tests/php7/methods/toString.phpt b/tests/php7/methods/toString.phpt
index 1e7e069..ed15138 100644
--- a/tests/php7/methods/toString.phpt
+++ b/tests/php7/methods/toString.phpt
@@ -17,7 +17,7 @@ $tests = [
     [0,             "0"],
     ["0",           "0"],
     ["+0",          "0"],
-    ["-0",         "-0"],
+    ["-0",          "0"],
     ["0.0",         "0.0"],
     ["1",           "1"],
     ["1.5",         "1.5"],
diff --git a/tests/php7/methods/truncate.phpt b/tests/php7/methods/truncate.phpt
index 5844f98..a9ab8bd 100644
--- a/tests/php7/methods/truncate.phpt
+++ b/tests/php7/methods/truncate.phpt
@@ -23,6 +23,8 @@ var_dump((string) decimal( "NAN")->truncate());
 var_dump((string) decimal( "INF")->truncate());
 var_dump((string) decimal("-INF")->truncate());
 
+var_dump((string) decimal("-0.1")->truncate());
+
 /**
  * Check that truncate does not modify the original
  */
@@ -38,4 +40,5 @@ string(1) "0"
 string(3) "NAN"
 string(3) "INF"
 string(4) "-INF"
+string(1) "0"
 string(5) "1.234"
diff --git a/tests/php7/serialize.phpt b/tests/php7/serialize.phpt
index 9470430..72b5d7b 100644
--- a/tests/php7/serialize.phpt
+++ b/tests/php7/serialize.phpt
@@ -10,6 +10,11 @@ use Decimal\Decimal;
 
 $decimal = new Decimal("1234.5678E+9", 42);
 
+var_dump(serialize($decimal));
+var_dump(unserialize(serialize($decimal)));
+
+$decimal = new Decimal("-0");
+
 var_dump(serialize($decimal));
 var_dump(unserialize(serialize($decimal)));
 ?>
@@ -21,3 +26,10 @@ object(Decimal\Decimal)#2 (2) {
   ["precision"]=>
   int(42)
 }
+string(41) "C:15:"Decimal\Decimal":13:{s:1:"0";i:28;}"
+object(Decimal\Decimal)#1 (2) {
+  ["value"]=>
+  string(1) "0"
+  ["precision"]=>
+  int(28)
+}