diff --git a/ext/mbstring/libmbfl/filters/mbfilter_cjk.c b/ext/mbstring/libmbfl/filters/mbfilter_cjk.c
index 4cdf129831278..13d088cf8e0a1 100644
--- a/ext/mbstring/libmbfl/filters/mbfilter_cjk.c
+++ b/ext/mbstring/libmbfl/filters/mbfilter_cjk.c
@@ -11560,6 +11560,45 @@ static void mb_wchar_to_cp936(uint32_t *in, size_t len, mb_convert_buf *buf, boo
 	MB_CONVERT_BUF_STORE(buf, out, limit);
 }
 
+/* Step through a GB18030 string one character at a time. Find the last position at or
+ * before `limit` which falls directly after the end of a (single or multi-byte) character */
+static zend_always_inline unsigned char* step_through_gb18030_str(unsigned char *p, unsigned char *limit)
+{
+	while (p < limit) {
+		unsigned char c = *p;
+		if (c < 0x81 || c == 0xFF) {
+			p++;
+		} else {
+			if (limit - p == 1) {
+				break;
+			}
+			unsigned char c2 = p[1];
+			/* For a 4-byte char, the 2nd byte will be 0x30-0x39 */
+			unsigned int w = (c2 >= 0x30 && c2 <= 0x39) ? 4 : 2;
+			if (limit - p < w) {
+				break;
+			}
+			p += w;
+		}
+	}
+	return p;
+}
+
+static zend_string* mb_cut_gb18030(unsigned char *str, size_t from, size_t len, unsigned char *end)
+{
+	ZEND_ASSERT(str + from <= end);
+	unsigned char *start = step_through_gb18030_str(str, str + from);
+	if (str + from + len > end) {
+		len = (end - str) - from;
+	}
+	if (start + len >= end) {
+		return zend_string_init_fast((const char*)start, end - start);
+	} else {
+		unsigned char *_end = step_through_gb18030_str(start, start + len);
+		return zend_string_init_fast((const char*)start, _end - start);
+	}
+}
+
 static const char *mbfl_encoding_gb18030_aliases[] = {"gb-18030", "gb-18030-2000", NULL};
 
 static const struct mbfl_convert_vtbl vtbl_gb18030_wchar = {
@@ -11594,7 +11633,7 @@ const mbfl_encoding mbfl_encoding_gb18030 = {
 	mb_gb18030_to_wchar,
 	mb_wchar_to_gb18030,
 	NULL,
-	NULL,
+	mb_cut_gb18030,
 };
 
 static const char *mbfl_encoding_cp936_aliases[] = {"CP-936", "GBK", NULL};
diff --git a/ext/mbstring/mbstring.c b/ext/mbstring/mbstring.c
index 14e7b71ed6287..237a2d2f62baf 100644
--- a/ext/mbstring/mbstring.c
+++ b/ext/mbstring/mbstring.c
@@ -2363,7 +2363,7 @@ PHP_FUNCTION(mb_strcut)
 	zend_string *encoding = NULL;
 	char *string_val;
 	zend_long from, len;
-	bool len_is_null = 1;
+	bool len_is_null = true;
 	mbfl_string string, result, *ret;
 
 	ZEND_PARSE_PARAMETERS_START(2, 4)
diff --git a/ext/mbstring/tests/mb_strcut.phpt b/ext/mbstring/tests/mb_strcut.phpt
index d94ac30ceaaf6..a3703cbdfc4c6 100644
--- a/ext/mbstring/tests/mb_strcut.phpt
+++ b/ext/mbstring/tests/mb_strcut.phpt
@@ -26,6 +26,7 @@ $jis = mb_convert_encoding("漢字 abc カナ", 'JIS', 'UTF-8');
 $iso2022jp2004 = mb_convert_encoding("漢字 abc カナ凜", 'ISO-2022-JP-2004', 'UTF-8'); // [1b242851 3441 3b7a 1b2842 20 61 62 63 20 1b242851 252b 254a 7425 1b2842]
 $iso2022jpms = mb_convert_encoding("漢字 abc カナ", 'ISO-2022-JP-MS', 'UTF-8'); // [1b2442 3441 3b7a 1b2842 20 61 62 63 20 1b2442 252b 254a 1b2842]
 $iso2022jp_kddi = mb_convert_encoding("漢字 abc カナ", 'ISO-2022-JP-KDDI', 'UTF-8');
+$gb18030 = mb_convert_encoding("漢字 abc カナ", 'GB18030', 'UTF-8');
 
 print "== EUC-JP ==\n";
 print MBStringChars(mb_strcut($euc_jp,  6,   5, 'EUC-JP'), 'EUC-JP') . "\n";
@@ -218,9 +219,37 @@ print "UTF-16 section is terminated improperly: [" . mb_strcut("&i6o\x83", 0, 10
 
 print "== GB18030 ==\n";
 
+print "Empty string: [" . bin2hex(mb_strcut("", 0, 5, 'GB18030')) . "]\n";
+print "Empty string 2: [" . bin2hex(mb_strcut("", -2, 1, 'GB18030')) . "]\n";
+print "Empty string 3: [" . bin2hex(mb_strcut("", 0, -1, 'GB18030')) . "]\n";
 print "Invalid byte 0xF5: [" . bin2hex(mb_strcut("\xF5a", 1, 100, 'GB18030')) . "]\n";
 print "Double-byte char: [" . bin2hex(mb_strcut("\xAFw", -1, 100, "GB18030")) . "]\n";
 
+print MBStringChars(mb_strcut($gb18030, 0, 0, 'GB18030'), 'GB18030') . "\n";
+print MBStringChars(mb_strcut($gb18030, 0, 1, 'GB18030'), 'GB18030') . "\n";
+print MBStringChars(mb_strcut($gb18030, 0, 2, 'GB18030'), 'GB18030') . "\n";
+print MBStringChars(mb_strcut($gb18030, 0, 3, 'GB18030'), 'GB18030') . "\n";
+print MBStringChars(mb_strcut($gb18030, 0, 4, 'GB18030'), 'GB18030') . "\n";
+print MBStringChars(mb_strcut($gb18030, 0, 5, 'GB18030'), 'GB18030') . "\n";
+print MBStringChars(mb_strcut($gb18030, 1, 2, 'GB18030'), 'GB18030') . "\n";
+print MBStringChars(mb_strcut($gb18030, 1, 3, 'GB18030'), 'GB18030') . "\n";
+print MBStringChars(mb_strcut($gb18030, 1, 4, 'GB18030'), 'GB18030') . "\n";
+
+// U+210A is encoded using 4 bytes in GB18030
+print "Operating on 4-byte GB18030 character:\n";
+$fourbyte = mb_convert_encoding("\x21\x0A", 'GB18030', 'UTF-16BE');
+print MBStringChars(mb_strcut($fourbyte, 0, 4, 'GB18030'), 'GB18030') . "\n";
+print MBStringChars(mb_strcut($fourbyte, 1, 4, 'GB18030'), 'GB18030') . "\n";
+print MBStringChars(mb_strcut($fourbyte, 2, 4, 'GB18030'), 'GB18030') . "\n";
+print MBStringChars(mb_strcut($fourbyte, 3, 4, 'GB18030'), 'GB18030') . "\n";
+print MBStringChars(mb_strcut($fourbyte, 4, 4, 'GB18030'), 'GB18030') . "\n";
+print MBStringChars(mb_strcut($fourbyte, 1, 3, 'GB18030'), 'GB18030') . "\n";
+print MBStringChars(mb_strcut($fourbyte, 2, 3, 'GB18030'), 'GB18030') . "\n";
+print MBStringChars(mb_strcut($fourbyte, 2, 4, 'GB18030'), 'GB18030') . "\n";
+print MBStringChars(mb_strcut($fourbyte, 0, -1, 'GB18030'), 'GB18030') . "\n";
+
+print "[" . bin2hex(mb_strcut(hex2bin("84308130"), 2, null, "GB18030")) . "]\n";
+
 print "== UHC ==\n";
 
 print "Single byte 0x96: [" . bin2hex(mb_strcut("\x96", 1, 1280, "UHC")) . "]\n";
@@ -405,8 +434,31 @@ UTF-16 section ends abruptly: []
 UTF-16 section ends abruptly in middle of 2nd codepoint: []
 UTF-16 section is terminated improperly: []
 == GB18030 ==
+Empty string: []
+Empty string 2: []
+Empty string 3: []
 Invalid byte 0xF5: []
 Double-byte char: []
+[]
+[]
+[9d68]
+[9d68]
+[9d68 d7d6]
+[9d68 d7d6 20]
+[9d68]
+[9d68]
+[9d68 d7d6]
+Operating on 4-byte GB18030 character:
+[8136bc32]
+[]
+[]
+[]
+[]
+[]
+[]
+[]
+[]
+[]
 == UHC ==
 Single byte 0x96: [96]
 == ASCII ==