diff --git a/Zend/tests/zend_ini/gh16886.phpt b/Zend/tests/zend_ini/gh16886.phpt
new file mode 100644
index 0000000000000..2e85894572359
--- /dev/null
+++ b/Zend/tests/zend_ini/gh16886.phpt
@@ -0,0 +1,41 @@
+--TEST--
+GH-16886 (ini_parse_quantity() fails to emit warning for 0x+0)
+--FILE--
+<?php
+echo ini_parse_quantity('0x 0'), "\n";
+echo ini_parse_quantity('0x+0'), "\n";
+echo ini_parse_quantity('0x-0'), "\n";
+echo ini_parse_quantity('0b 0'), "\n";
+echo ini_parse_quantity('0b+0'), "\n";
+echo ini_parse_quantity('0b-0'), "\n";
+echo ini_parse_quantity('0o 0'), "\n";
+echo ini_parse_quantity('0o+0'), "\n";
+echo ini_parse_quantity('0o-0'), "\n";
+?>
+--EXPECTF--
+Warning: Invalid quantity "0x 0": no digits after base prefix, interpreting as "0" for backwards compatibility in %s on line %d
+0
+
+Warning: Invalid quantity "0x+0": no digits after base prefix, interpreting as "0" for backwards compatibility in %s on line %d
+0
+
+Warning: Invalid quantity "0x-0": no digits after base prefix, interpreting as "0" for backwards compatibility in %s on line %d
+0
+
+Warning: Invalid quantity "0b 0": no digits after base prefix, interpreting as "0" for backwards compatibility in %s on line %d
+0
+
+Warning: Invalid quantity "0b+0": no digits after base prefix, interpreting as "0" for backwards compatibility in %s on line %d
+0
+
+Warning: Invalid quantity "0b-0": no digits after base prefix, interpreting as "0" for backwards compatibility in %s on line %d
+0
+
+Warning: Invalid quantity "0o 0": no digits after base prefix, interpreting as "0" for backwards compatibility in %s on line %d
+0
+
+Warning: Invalid quantity "0o+0": no digits after base prefix, interpreting as "0" for backwards compatibility in %s on line %d
+0
+
+Warning: Invalid quantity "0o-0": no digits after base prefix, interpreting as "0" for backwards compatibility in %s on line %d
+0
diff --git a/Zend/tests/zend_ini/gh16892.phpt b/Zend/tests/zend_ini/gh16892.phpt
new file mode 100644
index 0000000000000..05cfe02192e9d
--- /dev/null
+++ b/Zend/tests/zend_ini/gh16892.phpt
@@ -0,0 +1,22 @@
+--TEST--
+GH-16892 (ini_parse_quantity() fails to parse inputs starting with 0x0b)
+--FILE--
+<?php
+echo ini_parse_quantity('0x0b'), "\n";
+echo ini_parse_quantity('0xb'), "\n";
+echo ini_parse_quantity('-0x0B'), "\n";
+echo ini_parse_quantity('-0xB'), "\n";
+echo ini_parse_quantity('0x0beef'), "\n";
+echo ini_parse_quantity('0xbeef'), "\n";
+echo ini_parse_quantity('-0x0BEEF'), "\n";
+echo ini_parse_quantity('-0xBEEF'), "\n";
+?>
+--EXPECT--
+11
+11
+-11
+-11
+48879
+48879
+-48879
+-48879
diff --git a/Zend/zend_ini.c b/Zend/zend_ini.c
index 9588574df6cfb..f5d178073066e 100644
--- a/Zend/zend_ini.c
+++ b/Zend/zend_ini.c
@@ -587,7 +587,7 @@ typedef enum {
 	ZEND_INI_PARSE_QUANTITY_UNSIGNED,
 } zend_ini_parse_quantity_signed_result_t;
 
-static const char *zend_ini_consume_quantity_prefix(const char *const digits, const char *const str_end) {
+static const char *zend_ini_consume_quantity_prefix(const char *const digits, const char *const str_end, int base) {
 	const char *digits_consumed = digits;
 	/* Ignore leading whitespace. */
 	while (digits_consumed < str_end && zend_is_whitespace(*digits_consumed)) {++digits_consumed;}
@@ -598,7 +598,7 @@ static const char *zend_ini_consume_quantity_prefix(const char *const digits, co
 	if (digits_consumed[0] == '0' && !isdigit(digits_consumed[1])) {
 		/* Value is just 0 */
 		if ((digits_consumed+1) == str_end) {
-			return digits;
+			return digits_consumed;
 		}
 
 		switch (digits_consumed[1]) {
@@ -606,9 +606,14 @@ static const char *zend_ini_consume_quantity_prefix(const char *const digits, co
 			case 'X':
 			case 'o':
 			case 'O':
+				digits_consumed += 2;
+				break;
 			case 'b':
 			case 'B':
-				digits_consumed += 2;
+				if (base != 16) {
+					/* 0b or 0B is valid in base 16, but not in the other supported bases. */
+					digits_consumed += 2;
+				}
 				break;
 		}
 	}
@@ -696,19 +701,7 @@ static zend_ulong zend_ini_parse_quantity_internal(zend_string *value, zend_ini_
 				return 0;
         }
         digits += 2;
-		if (UNEXPECTED(digits == str_end)) {
-			/* Escape the string to avoid null bytes and to make non-printable chars
-			 * visible */
-			smart_str_append_escaped(&invalid, ZSTR_VAL(value), ZSTR_LEN(value));
-			smart_str_0(&invalid);
-
-			*errstr = zend_strpprintf(0, "Invalid quantity \"%s\": no digits after base prefix, interpreting as \"0\" for backwards compatibility",
-							ZSTR_VAL(invalid.s));
-
-			smart_str_free(&invalid);
-			return 0;
-		}
-		if (UNEXPECTED(digits != zend_ini_consume_quantity_prefix(digits, str_end))) {
+		if (UNEXPECTED(digits == str_end || digits != zend_ini_consume_quantity_prefix(digits, str_end, base))) {
 			/* Escape the string to avoid null bytes and to make non-printable chars
 			 * visible */
 			smart_str_append_escaped(&invalid, ZSTR_VAL(value), ZSTR_LEN(value));