diff --git a/ext/mbstring/libmbfl/filters/mbfilter_singlebyte.c b/ext/mbstring/libmbfl/filters/mbfilter_singlebyte.c
index f2973b92095..56c9b2dbc85 100644
--- a/ext/mbstring/libmbfl/filters/mbfilter_singlebyte.c
+++ b/ext/mbstring/libmbfl/filters/mbfilter_singlebyte.c
@@ -485,10 +485,10 @@ DEF_SB_TBL(cp1251, "Windows-1251", "Windows-1251", cp1251_aliases, 0x80, cp1251_
 
 static const char *cp1252_aliases[] = {"cp1252", NULL};
 static const unsigned short cp1252_ucs_table[] = {
-	0x20AC, 0x0000, 0x201A, 0x0192, 0x201E, 0x2026, 0x2020, 0x2021,
-	0x02C6, 0x2030, 0x0160, 0x2039, 0x0152, 0x0000, 0x017D, 0x0000,
-	0x0000, 0x2018, 0x2019, 0x201C, 0x201D, 0x2022, 0x2013, 0x2014,
-	0x02DC, 0x2122, 0x0161, 0x203A, 0x0153, 0x0000, 0x017E, 0x0178
+	0x20AC, 0x0081, 0x201A, 0x0192, 0x201E, 0x2026, 0x2020, 0x2021,
+	0x02C6, 0x2030, 0x0160, 0x2039, 0x0152, 0x008D, 0x017D, 0x008F,
+	0x0090, 0x2018, 0x2019, 0x201C, 0x201D, 0x2022, 0x2013, 0x2014,
+	0x02DC, 0x2122, 0x0161, 0x203A, 0x0153, 0x009D, 0x017E, 0x0178
 };
 DEF_SB(cp1252, "Windows-1252", "Windows-1252", cp1252_aliases);
 
@@ -504,7 +504,7 @@ static int mbfl_filt_conv_wchar_cp1252(int c, mbfl_convert_filter *filter)
 			}
 		}
 		CK(mbfl_filt_conv_illegal_output(c, filter));
-	} else if (c <= 0x7F || c >= 0xA0) {
+	} else if (c <= 0x7F || c >= 0xA0 || c == 0x81 || c == 0x8D || c == 0x8F || c == 0x90 || c == 0x9D) {
 		CK((*filter->output_function)(c, filter->data));
 	} else {
 		CK(mbfl_filt_conv_illegal_output(c, filter));
@@ -562,7 +562,7 @@ static void mb_wchar_to_cp1252(uint32_t *in, size_t len, mb_convert_buf *buf, bo
 			}
 			MB_CONVERT_ERROR(buf, out, limit, w, mb_wchar_to_cp1252);
 			MB_CONVERT_BUF_ENSURE(buf, out, limit, len);
-		} else if (w <= 0x7F || w >= 0xA0) {
+		} else if (w <= 0x7F || w >= 0xA0 || w == 0x81 || w == 0x8D || w == 0x8F || w == 0x90 || w == 0x9D) {
 			out = mb_convert_buf_add(out, w);
 		} else {
 			MB_CONVERT_ERROR(buf, out, limit, w, mb_wchar_to_cp1252);
diff --git a/ext/mbstring/tests/cp1252_encoding.phpt b/ext/mbstring/tests/cp1252_encoding.phpt
index 0688fe94313..228dfde905c 100644
--- a/ext/mbstring/tests/cp1252_encoding.phpt
+++ b/ext/mbstring/tests/cp1252_encoding.phpt
@@ -11,11 +11,6 @@ if (getenv("SKIP_SLOW_TESTS")) die("skip slow test");
 include('encoding_tests.inc');
 testEncodingFromUTF16ConversionTable(__DIR__ . '/data/CP1252.txt', 'CP1252');
 
-// Test "long" illegal character markers
-mb_substitute_character("long");
-convertInvalidString("\x81", "%", "CP1252", "UTF-8");
-convertInvalidString("\x9D", "%", "CP1252", "UTF-8");
-
 // Test replacement character which cannot be encoded in CP1252
 mb_substitute_character(0x1234);
 convertInvalidString("\x23\x45", '?', 'UTF-16BE', 'CP1252');
diff --git a/ext/mbstring/tests/data/CP1252.txt b/ext/mbstring/tests/data/CP1252.txt
index 8ff4b204b75..0ccd4ff1898 100644
--- a/ext/mbstring/tests/data/CP1252.txt
+++ b/ext/mbstring/tests/data/CP1252.txt
@@ -145,7 +145,7 @@
 0x7E	0x007E	#TILDE
 0x7F	0x007F	#DELETE
 0x80	0x20AC	#EURO SIGN
-0x81	      	#UNDEFINED
+0x81	0x0081	#*** MODIFIED TO FOLLOW WINDOWS "BEST FIT" MAPPINGS
 0x82	0x201A	#SINGLE LOW-9 QUOTATION MARK
 0x83	0x0192	#LATIN SMALL LETTER F WITH HOOK
 0x84	0x201E	#DOUBLE LOW-9 QUOTATION MARK
@@ -157,10 +157,10 @@
 0x8A	0x0160	#LATIN CAPITAL LETTER S WITH CARON
 0x8B	0x2039	#SINGLE LEFT-POINTING ANGLE QUOTATION MARK
 0x8C	0x0152	#LATIN CAPITAL LIGATURE OE
-0x8D	      	#UNDEFINED
+0x8D	0x008D	#*** MODIFIED TO FOLLOW WINDOWS "BEST FIT" MAPPINGS
 0x8E	0x017D	#LATIN CAPITAL LETTER Z WITH CARON
-0x8F	      	#UNDEFINED
-0x90	      	#UNDEFINED
+0x8F	0x008F	#*** MODIFIED TO FOLLOW WINDOWS "BEST FIT" MAPPINGS
+0x90	0x0090	#*** MODIFIED TO FOLLOW WINDOWS "BEST FIT" MAPPINGS
 0x91	0x2018	#LEFT SINGLE QUOTATION MARK
 0x92	0x2019	#RIGHT SINGLE QUOTATION MARK
 0x93	0x201C	#LEFT DOUBLE QUOTATION MARK
@@ -173,7 +173,7 @@
 0x9A	0x0161	#LATIN SMALL LETTER S WITH CARON
 0x9B	0x203A	#SINGLE RIGHT-POINTING ANGLE QUOTATION MARK
 0x9C	0x0153	#LATIN SMALL LIGATURE OE
-0x9D	      	#UNDEFINED
+0x9D	0x009D	#*** MODIFIED TO FOLLOW WINDOWS "BEST FIT" MAPPINGS
 0x9E	0x017E	#LATIN SMALL LETTER Z WITH CARON
 0x9F	0x0178	#LATIN CAPITAL LETTER Y WITH DIAERESIS
 0xA0	0x00A0	#NO-BREAK SPACE