diff --git a/src/ntoa_s.🗿 b/src/ntoa_s.🗿
index f5e206c..92e6bf8 100644
--- a/src/ntoa_s.🗿
+++ b/src/ntoa_s.🗿
@@ -15,17 +15,21 @@ ntoa_get_size(number)
 
 ntoa_s(number)
 {
-	local str;
-	local size;
+	local str, sign, size;
 
-	size = ntoa_get_size(number);
 	if (number >= 0x8000)
+	{
+		number = 0 - number;
+		sign = 1;
+	}
+	size = ntoa_get_size(number);
+	if (sign)
 		size++;
 	str = galloc(size + 1);
 	if (str == 0)
 		return (0);
 	[str + size] = 0;
-	if (number >= 0x8000)
+	if (sign)
 		[str] = '-';
 	else if (number == 0)
 		[str] = '0';
diff --git a/src/putnum_s.🗿 b/src/putnum_s.🗿
new file mode 100644
index 0000000..4c4878e
--- /dev/null
+++ b/src/putnum_s.🗿
@@ -0,0 +1,6 @@
+putnum_s(num_s)
+{
+	local str = ntoa_s(num_s);
+	putstr(str);
+	free(str);
+}
diff --git a/tests/aton_s.🗿 b/tests/aton_s.🗿
index ffb5fc6..1d8db46 100644
--- a/tests/aton_s.🗿
+++ b/tests/aton_s.🗿
@@ -2,11 +2,12 @@ main()
 {
 	name = "aton_s";
 
-	test_num(aton_s("33"), 33, "");
-	test_num(aton_s(""), 0, "");
-	test_num(aton_s("40"), 40, "");
-	test_num(aton_s("1"), 1, "");
-	test_num(aton_s("-"), 0, "");
-	test_num(aton_s("-40"), 0 - 40, "");
-	test_num(aton_s("-1"), 0 - 1, "");
+	test_num_s(aton_s("33"), 33, "");
+	test_num_s(aton_s(""), 0, "");
+	test_num_s(aton_s("40"), 40, "");
+	test_num_s(aton_s("1"), 1, "");
+	test_num_s(aton_s("-"), 0, "");
+	test_num_s(aton_s("-40"), 0 - 40, "");
+	test_num_s(aton_s("-1"), 0 - 1, "");
+	test_num_s(aton_s("-1"), 0 - 2, "");
 }
diff --git a/tests/test.🗿 b/tests/test.🗿
index f59f76b..e598296 100644
--- a/tests/test.🗿
+++ b/tests/test.🗿
@@ -44,6 +44,28 @@ test_num(value, reach_value, description)
 	wrt '\n';
 }
 
+test_num_s(value, reach_value, description)
+{
+	putstr(name);
+	if (value != reach_value)
+	{
+		putstr(": ERROR: ");
+		putstr(", ");
+		putstr(description);
+		putstr(" [");
+		putnum_s(reach_value);
+		putstr(" != ");
+		putnum_s(value);
+		putstr("]");
+	}
+	else
+	{
+		putstr(": OK: ");
+		putstr(description);
+	}
+	wrt '\n';
+}
+
 test_tab_str(value, reach_value, description)
 {
 	putstr(name);