diff --git a/ext/mbstring/mbstring.c b/ext/mbstring/mbstring.c
index e219a6bdb79..d0d724f640a 100644
--- a/ext/mbstring/mbstring.c
+++ b/ext/mbstring/mbstring.c
@@ -2878,7 +2878,7 @@ PHP_FUNCTION(mb_convert_encoding)
 
 static zend_string *mbstring_convert_case(php_case_mode case_mode, const char *str, size_t str_len, const mbfl_encoding *enc)
 {
-	return php_unicode_convert_case(case_mode, str, str_len, enc, MBSTRG(current_filter_illegal_mode), MBSTRG(current_filter_illegal_substchar));
+	return php_unicode_convert_case(case_mode, str, str_len, enc, enc, MBSTRG(current_filter_illegal_mode), MBSTRG(current_filter_illegal_substchar));
 }
 
 PHP_FUNCTION(mb_convert_case)
@@ -4858,10 +4858,10 @@ MBSTRING_API size_t php_mb_stripos(bool mode, zend_string *haystack, zend_string
 {
 	/* We're using simple case-folding here, because we'd have to deal with remapping of
 	 * offsets otherwise. */
-	zend_string *haystack_conv = mbstring_convert_case(PHP_UNICODE_CASE_FOLD_SIMPLE, ZSTR_VAL(haystack), ZSTR_LEN(haystack), enc);
-	zend_string *needle_conv = mbstring_convert_case(PHP_UNICODE_CASE_FOLD_SIMPLE, ZSTR_VAL(needle), ZSTR_LEN(needle), enc);
+	zend_string *haystack_conv = php_unicode_convert_case(PHP_UNICODE_CASE_FOLD_SIMPLE, ZSTR_VAL(haystack), ZSTR_LEN(haystack), enc, &mbfl_encoding_utf8, MBSTRG(current_filter_illegal_mode), MBSTRG(current_filter_illegal_substchar));
+	zend_string *needle_conv = php_unicode_convert_case(PHP_UNICODE_CASE_FOLD_SIMPLE, ZSTR_VAL(needle), ZSTR_LEN(needle), enc, &mbfl_encoding_utf8, MBSTRG(current_filter_illegal_mode), MBSTRG(current_filter_illegal_substchar));
 
-	size_t n = mb_find_strpos(haystack_conv, needle_conv, enc, offset, mode);
+	size_t n = mb_find_strpos(haystack_conv, needle_conv, &mbfl_encoding_utf8, offset, mode);
 
 	zend_string_free(haystack_conv);
 	zend_string_free(needle_conv);
diff --git a/ext/mbstring/php_unicode.c b/ext/mbstring/php_unicode.c
index e07490c884e..bd1d5684163 100644
--- a/ext/mbstring/php_unicode.c
+++ b/ext/mbstring/php_unicode.c
@@ -238,7 +238,7 @@ static uint32_t *emit_special_casing_sequence(uint32_t w, uint32_t *out)
 	return out;
 }
 
-MBSTRING_API zend_string *php_unicode_convert_case(php_case_mode case_mode, const char *srcstr, size_t in_len, const mbfl_encoding *src_encoding, int illegal_mode, uint32_t illegal_substchar)
+MBSTRING_API zend_string *php_unicode_convert_case(php_case_mode case_mode, const char *srcstr, size_t in_len, const mbfl_encoding *src_encoding, const mbfl_encoding *dst_encoding, int illegal_mode, uint32_t illegal_substchar)
 {
 	/* A Unicode codepoint can expand out to up to 3 codepoints when uppercased, lowercased, or title cased
 	 * See http://www.unicode.org/Public/UNIDATA/SpecialCasing.txt */
@@ -363,7 +363,7 @@ MBSTRING_API zend_string *php_unicode_convert_case(php_case_mode case_mode, cons
 		}
 
 		ZEND_ASSERT(p - converted_buf <= 192);
-		src_encoding->from_wchar(converted_buf, p - converted_buf, &buf, !in_len);
+		dst_encoding->from_wchar(converted_buf, p - converted_buf, &buf, !in_len);
 	}
 
 	return mb_convert_buf_result(&buf);
diff --git a/ext/mbstring/php_unicode.h b/ext/mbstring/php_unicode.h
index b65b347df1b..1326761943d 100644
--- a/ext/mbstring/php_unicode.h
+++ b/ext/mbstring/php_unicode.h
@@ -91,7 +91,7 @@ typedef enum {
 
 MBSTRING_API zend_string *php_unicode_convert_case(
 		php_case_mode case_mode, const char *srcstr, size_t srclen,
-		const mbfl_encoding *src_encoding, int illegal_mode, uint32_t illegal_substchar);
+		const mbfl_encoding *src_encoding, const mbfl_encoding *dst_encoding, int illegal_mode, uint32_t illegal_substchar);
 
 /* Optimize the common ASCII case for lower/upper */
 
diff --git a/ext/mbstring/tests/mb_stripos.phpt b/ext/mbstring/tests/mb_stripos.phpt
index 1383cd5ed2e..7f4898a0f51 100644
--- a/ext/mbstring/tests/mb_stripos.phpt
+++ b/ext/mbstring/tests/mb_stripos.phpt
@@ -9,9 +9,8 @@ mbstring
 ini_set('include_path','.');
 include_once('common.inc');
 
-
 // Test string
-$euc_jp = '0123この文字列は日本語です。EUC-JPを使っています。0123日本語は面倒臭い。';
+$euc_jp = "0123\xA4\xB3\xA4\xCE\xCA\xB8\xBB\xFA\xCE\xF3\xA4\xCF\xC6\xFC\xCB\xDC\xB8\xEC\xA4\xC7\xA4\xB9\xA1\xA3EUC-JP\xA4\xF2\xBB\xC8\xA4\xC3\xA4\xC6\xA4\xA4\xA4\xDE\xA4\xB9\xA1\xA30123\xC6\xFC\xCB\xDC\xB8\xEC\xA4\xCF\xCC\xCC\xC5\xDD\xBD\xAD\xA4\xA4\xA1\xA3";
 
 $slen = mb_strlen($euc_jp, 'EUC-JP');
 echo "String len: $slen\n";
@@ -21,11 +20,11 @@ mb_internal_encoding('UTF-8') or print("mb_internal_encoding() failed\n");
 
 echo  "== POSITIVE OFFSET ==\n";
 
-print  mb_stripos($euc_jp, '日本語', 0, 'EUC-JP') . "\n";
+print  mb_stripos($euc_jp, "\xC6\xFC\xCB\xDC\xB8\xEC", 0, 'EUC-JP') . "\n";
 print  mb_stripos($euc_jp, '0', 0,     'EUC-JP') . "\n";
 print  mb_stripos($euc_jp, 3, 0,       'EUC-JP') . "\n";
 print  mb_stripos($euc_jp, 0, 0,       'EUC-JP') . "\n";
-print  mb_stripos($euc_jp, '日本語', 15, 'EUC-JP') . "\n";
+print  mb_stripos($euc_jp, "\xC6\xFC\xCB\xDC\xB8\xEC", 15, 'EUC-JP') . "\n";
 print  mb_stripos($euc_jp, '0', 15,     'EUC-JP') . "\n";
 print  mb_stripos($euc_jp, 3, 15,       'EUC-JP') . "\n";
 print  mb_stripos($euc_jp, 0, 15,       'EUC-JP') . "\n";
@@ -34,7 +33,7 @@ print  mb_stripos($euc_jp, 0, 15,       'EUC-JP') . "\n";
 // Negative offset
 echo "== NEGATIVE OFFSET ==\n";
 
-print mb_stripos($euc_jp, '日本語', -15, 'EUC-JP') . "\n";
+print mb_stripos($euc_jp, "\xC6\xFC\xCB\xDC\xB8\xEC", -15, 'EUC-JP') . "\n";
 print mb_stripos($euc_jp, '0', -15,     'EUC-JP') . "\n";
 print mb_stripos($euc_jp, 3, -15,       'EUC-JP') . "\n";
 print mb_stripos($euc_jp, 0, -15,       'EUC-JP') . "\n";
@@ -44,7 +43,7 @@ print mb_stripos($euc_jp, 0, -43,       'EUC-JP') . "\n";
 // Out of range - should return false
 print ("== OUT OF RANGE ==\n");
 
-$r =  mb_stripos($euc_jp, '日本語', 40, 'EUC-JP');
+$r =  mb_stripos($euc_jp, "\xC6\xFC\xCB\xDC\xB8\xEC", 40, 'EUC-JP');
 ($r === FALSE) ? print "OK_OUT_RANGE\n"     : print "NG_OUT_RANGE\n";
 $r =  mb_stripos($euc_jp, '0', 40,     'EUC-JP');
 ($r === FALSE) ? print "OK_OUT_RANGE\n"     : print "NG_OUT_RANGE\n";
@@ -52,7 +51,7 @@ $r =  mb_stripos($euc_jp, 3, 40,       'EUC-JP');
 ($r === FALSE) ? print "OK_OUT_RANGE\n"     : print "NG_OUT_RANGE\n";
 $r =   mb_stripos($euc_jp, 0, 40,       'EUC-JP');
 ($r === FALSE) ? print "OK_OUT_RANGE\n"     : print "NG_OUT_RANGE\n";
-$r =  mb_stripos($euc_jp, '日本語', -3, 'EUC-JP');
+$r =  mb_stripos($euc_jp, "\xC6\xFC\xCB\xDC\xB8\xEC", -3, 'EUC-JP');
 ($r === FALSE) ? print "OK_OUT_RANGE\n"     : print "NG_OUT_RANGE\n";
 $r =  mb_stripos($euc_jp, '0', -3,     'EUC-JP');
 ($r === FALSE) ? print "OK_OUT_RANGE\n"     : print "NG_OUT_RANGE\n";
@@ -65,7 +64,7 @@ $r =   mb_stripos($euc_jp, 0, -3,       'EUC-JP');
 // Non-existent
 echo "== NON-EXISTENT ==\n";
 
-$r = mb_stripos($euc_jp, '韓国語', 0, 'EUC-JP');
+$r = mb_stripos($euc_jp, "\xB4\xDA\xB9\xF1\xB8\xEC", 0, 'EUC-JP');
 ($r === FALSE) ? print "OK_STR\n"     : print "NG_STR\n";
 $r = mb_stripos($euc_jp, "\n",     0, 'EUC-JP');
 ($r === FALSE) ? print "OK_NEWLINE\n" : print "NG_NEWLINE\n";
@@ -76,12 +75,12 @@ echo "== NO ENCODING PARAMETER ==\n";
 
 mb_internal_encoding('EUC-JP')  or print("mb_internal_encoding() failed\n");
 
-print  mb_stripos($euc_jp, '日本語', 0) . "\n";
+print  mb_stripos($euc_jp, "\xC6\xFC\xCB\xDC\xB8\xEC", 0) . "\n";
 print  mb_stripos($euc_jp, '0', 0) . "\n";
 print  mb_stripos($euc_jp, 3, 0) . "\n";
 print  mb_stripos($euc_jp, 0, 0) . "\n";
 
-$r = mb_stripos($euc_jp, '韓国語', 0);
+$r = mb_stripos($euc_jp, "\xB4\xDA\xB9\xF1\xB8\xEC", 0);
 ($r === FALSE) ? print "OK_STR\n"     : print "NG_STR\n";
 $r = mb_stripos($euc_jp, "\n", 0);
 ($r === FALSE) ? print "OK_NEWLINE\n" : print "NG_NEWLINE\n";
@@ -91,12 +90,12 @@ echo "== NO OFFSET AND ENCODING PARAMETER ==\n";
 
 mb_internal_encoding('EUC-JP')  or print("mb_internal_encoding() failed\n");
 
-print  mb_stripos($euc_jp, '日本語') . "\n";
+print  mb_stripos($euc_jp, "\xC6\xFC\xCB\xDC\xB8\xEC") . "\n";
 print  mb_stripos($euc_jp, '0') . "\n";
 print  mb_stripos($euc_jp, 3) . "\n";
 print  mb_stripos($euc_jp, 0) . "\n";
 
-$r = mb_stripos($euc_jp, '韓国語');
+$r = mb_stripos($euc_jp, "\xB4\xDA\xB9\xF1\xB8\xEC");
 ($r === FALSE) ? print "OK_STR\n"     : print "NG_STR\n";
 $r = mb_stripos($euc_jp, "\n");
 ($r === FALSE) ? print "OK_NEWLINE\n" : print "NG_NEWLINE\n";