diff --git a/mingw-w64-crt/lib-common/api-ms-win-crt-convert-l1-1-0.def.in b/mingw-w64-crt/lib-common/api-ms-win-crt-convert-l1-1-0.def.in
index fd49dc0..5542649 100644
--- a/mingw-w64-crt/lib-common/api-ms-win-crt-convert-l1-1-0.def.in
+++ b/mingw-w64-crt/lib-common/api-ms-win-crt-convert-l1-1-0.def.in
@@ -93,7 +93,7 @@
 atoi
 atol
 atoll
-; btowc ; use replacement
+; btowc ; replaced for consistency with wctob
 c16rtomb
 c32rtomb
 mbrtoc16
@@ -128,7 +128,7 @@
 wcstoul
 wcstoull
 wcstoumax
-; wctob ; use replacement
+; wctob ; replaced, CRT version may sign-extend its return value
 wctomb
 wctomb_s
 wctrans
diff --git a/mingw-w64-crt/lib-common/msvcr120_app.def.in b/mingw-w64-crt/lib-common/msvcr120_app.def.in
index 083b1f2..3f0e890 100644
--- a/mingw-w64-crt/lib-common/msvcr120_app.def.in
+++ b/mingw-w64-crt/lib-common/msvcr120_app.def.in
@@ -1877,7 +1877,7 @@
 atoll
 bsearch
 bsearch_s
-; btowc ; use replacement
+; btowc ; replaced for consistency with wctob
 cabs
 cabsf
 F_ARM32(cabsl) ; Can't use long double functions from the CRT on x86
@@ -2321,7 +2321,7 @@
 wcstoull
 wcstoumax
 wcsxfrm
-; wctob ; use replacement
+; wctob ; replaced, CRT version may sign-extend its return value
 wctomb
 wctomb_s
 wctrans
diff --git a/mingw-w64-crt/lib-common/msvcrt.def.in b/mingw-w64-crt/lib-common/msvcrt.def.in
index a7bb31f..0476000 100644
--- a/mingw-w64-crt/lib-common/msvcrt.def.in
+++ b/mingw-w64-crt/lib-common/msvcrt.def.in
@@ -1795,7 +1795,7 @@
 _wutime32 F_I386(== _wutime) ; i386 _wutime32 replaced by alias
 F_ARM_ANY(asctime_s) ; i386 and x64 asctime_s replaced by emu
 bsearch_s
-; F_ARM_ANY(btowc) ; always use replacement
+; F_ARM_ANY(btowc) ; replaced for consistency with wctob
 clearerr_s
 fopen_s
 fprintf_s
@@ -1849,7 +1849,7 @@
 wcsrtombs_s
 F_ARM_ANY(wcstok_s) ; i386 and x64 wcstok_s replaced by emu
 wcstombs_s
-; F_ARM_ANY(wctob) ; always use replacement
+; F_ARM_ANY(wctob) ; replaced, CRT version may sign-extend its return value
 wctomb_s
 wprintf_s
 wscanf_s
diff --git a/mingw-w64-crt/lib-common/ucrtbase-common.def.in b/mingw-w64-crt/lib-common/ucrtbase-common.def.in
index dd4f081..c0a273e 100644
--- a/mingw-w64-crt/lib-common/ucrtbase-common.def.in
+++ b/mingw-w64-crt/lib-common/ucrtbase-common.def.in
@@ -2233,7 +2233,7 @@
 atoll
 bsearch
 bsearch_s
-; btowc ; use replacement
+; btowc ; replaced for consistency with wctob
 c16rtomb
 c32rtomb
 cabs
@@ -2656,7 +2656,7 @@
 wcstoull
 wcstoumax
 wcsxfrm
-; wctob ; use replacement
+; wctob ; replaced, CRT version may sign-extend its return value
 wctomb
 wctomb_s
 wctrans
diff --git a/mingw-w64-crt/lib32/msvcr100.def.in b/mingw-w64-crt/lib32/msvcr100.def.in
index 4016060..58542e5 100644
--- a/mingw-w64-crt/lib32/msvcr100.def.in
+++ b/mingw-w64-crt/lib32/msvcr100.def.in
@@ -1662,7 +1662,7 @@
 atol
 bsearch
 bsearch_s
-; btowc ; use replacement
+; btowc ; replaced for consistency with wctob
 calloc
 ceil DATA
 clearerr
@@ -1892,7 +1892,7 @@
 wcstombs_s
 wcstoul
 wcsxfrm
-; wctob ; use replacement
+; wctob ; replaced, CRT version may sign-extend its return value
 wctomb
 wctomb_s
 wmemcpy_s
diff --git a/mingw-w64-crt/lib32/msvcr100d.def.in b/mingw-w64-crt/lib32/msvcr100d.def.in
index 40d9e34..8534faa 100644
--- a/mingw-w64-crt/lib32/msvcr100d.def.in
+++ b/mingw-w64-crt/lib32/msvcr100d.def.in
@@ -1729,7 +1729,7 @@
 atol
 bsearch
 bsearch_s
-; btowc ; use replacement
+; btowc ; replaced for consistency with wctob
 calloc
 ceil DATA ; overwritten
 clearerr
@@ -1955,7 +1955,7 @@
 wcstombs_s
 wcstoul
 wcsxfrm
-; wctob ; use replacement
+; wctob ; replaced, CRT version may sign-extend its return value
 wctomb
 wctomb_s
 wmemcpy_s
diff --git a/mingw-w64-crt/lib32/msvcr110.def.in b/mingw-w64-crt/lib32/msvcr110.def.in
index eb8c50d..e6894b9 100644
--- a/mingw-w64-crt/lib32/msvcr110.def.in
+++ b/mingw-w64-crt/lib32/msvcr110.def.in
@@ -1795,7 +1795,7 @@
 atol
 bsearch
 bsearch_s
-; btowc ; use replacement
+; btowc ; replaced for consistency with wctob
 calloc
 ceil DATA
 clearerr
@@ -2021,7 +2021,7 @@
 wcstombs_s
 wcstoul
 wcsxfrm
-; wctob ; use replacement
+; wctob ; replaced, CRT version may sign-extend its return value
 wctomb
 wctomb_s
 wmemcpy_s
diff --git a/mingw-w64-crt/lib32/msvcr110d.def.in b/mingw-w64-crt/lib32/msvcr110d.def.in
index cae1990..38d99e2 100644
--- a/mingw-w64-crt/lib32/msvcr110d.def.in
+++ b/mingw-w64-crt/lib32/msvcr110d.def.in
@@ -1862,7 +1862,7 @@
 atol
 bsearch
 bsearch_s
-; btowc ; use replacement
+; btowc ; replaced for consistency with wctob
 calloc
 ceil DATA ; overwritten
 clearerr
@@ -2088,7 +2088,7 @@
 wcstombs_s
 wcstoul
 wcsxfrm
-; wctob ; use replacement
+; wctob ; replaced, CRT version may sign-extend its return value
 wctomb
 wctomb_s
 wmemcpy_s
diff --git a/mingw-w64-crt/lib32/msvcr120.def.in b/mingw-w64-crt/lib32/msvcr120.def.in
index 385567b..7571463 100644
--- a/mingw-w64-crt/lib32/msvcr120.def.in
+++ b/mingw-w64-crt/lib32/msvcr120.def.in
@@ -1853,7 +1853,7 @@
 atoll
 bsearch
 bsearch_s
-; btowc ; use replacement
+; btowc ; replaced for consistency with wctob
 cabs
 cabsf
 ; cabsl ; Can't use long double functions from the CRT on x86
@@ -2284,7 +2284,7 @@
 wcstoull
 wcstoumax
 wcsxfrm
-; wctob ; use replacement
+; wctob ; replaced, CRT version may sign-extend its return value
 wctomb
 wctomb_s
 wctrans
diff --git a/mingw-w64-crt/lib32/msvcr120d.def.in b/mingw-w64-crt/lib32/msvcr120d.def.in
index eb02578..fb75756 100644
--- a/mingw-w64-crt/lib32/msvcr120d.def.in
+++ b/mingw-w64-crt/lib32/msvcr120d.def.in
@@ -1920,7 +1920,7 @@
 atoll
 bsearch
 bsearch_s
-; btowc ; use replacement
+; btowc ; replaced for consistency with wctob
 cabs
 cabsf
 ; cabsl ; Can't use long double functions from the CRT on x86
@@ -2351,7 +2351,7 @@
 wcstoull
 wcstoumax
 wcsxfrm
-; wctob ; use replacement
+; wctob ; replaced, CRT version may sign-extend its return value
 wctomb
 wctomb_s
 wctrans
diff --git a/mingw-w64-crt/lib32/msvcr80.def.in b/mingw-w64-crt/lib32/msvcr80.def.in
index f3f78df..cbc51da 100644
--- a/mingw-w64-crt/lib32/msvcr80.def.in
+++ b/mingw-w64-crt/lib32/msvcr80.def.in
@@ -1303,7 +1303,7 @@
 atol
 bsearch
 bsearch_s
-; btowc ; use replacement
+; btowc ; replaced for consistency with wctob
 calloc
 ceil DATA
 clearerr
@@ -1526,7 +1526,7 @@
 wcstombs_s
 wcstoul
 wcsxfrm
-; wctob ; use replacement
+; wctob ; replaced, CRT version may sign-extend its return value
 wctomb
 wctomb_s
 wprintf
diff --git a/mingw-w64-crt/lib32/msvcr80d.def.in b/mingw-w64-crt/lib32/msvcr80d.def.in
index 0df1c12..dc83410 100644
--- a/mingw-w64-crt/lib32/msvcr80d.def.in
+++ b/mingw-w64-crt/lib32/msvcr80d.def.in
@@ -1386,7 +1386,7 @@
 atol
 bsearch
 bsearch_s
-; btowc ; use replacement
+; btowc ; replaced for consistency with wctob
 calloc
 ceil DATA ; overwritten
 clearerr
@@ -1609,7 +1609,7 @@
 wcstombs_s
 wcstoul
 wcsxfrm
-; wctob ; use replacement
+; wctob ; replaced, CRT version may sign-extend its return value
 wctomb
 wctomb_s
 wprintf
diff --git a/mingw-w64-crt/lib32/msvcr90.def.in b/mingw-w64-crt/lib32/msvcr90.def.in
index bfb97ff..4455d1e 100644
--- a/mingw-w64-crt/lib32/msvcr90.def.in
+++ b/mingw-w64-crt/lib32/msvcr90.def.in
@@ -1296,7 +1296,7 @@
 atol
 bsearch
 bsearch_s
-; btowc ; use replacement
+; btowc ; replaced for consistency with wctob
 calloc
 ceil DATA
 clearerr
@@ -1524,7 +1524,7 @@
 wcstombs_s
 wcstoul
 wcsxfrm
-; wctob ; use replacement
+; wctob ; replaced, CRT version may sign-extend its return value
 wctomb
 wctomb_s
 wprintf
diff --git a/mingw-w64-crt/lib32/msvcr90d.def.in b/mingw-w64-crt/lib32/msvcr90d.def.in
index 69f0d8e..19f6f4a 100644
--- a/mingw-w64-crt/lib32/msvcr90d.def.in
+++ b/mingw-w64-crt/lib32/msvcr90d.def.in
@@ -1368,7 +1368,7 @@
 atol
 bsearch
 bsearch_s
-; btowc ; use replacement
+; btowc ; replaced for consistency with wctob
 calloc
 ceil DATA
 clearerr
@@ -1596,7 +1596,7 @@
 wcstombs_s
 wcstoul
 wcsxfrm
-; wctob ; use replacement
+; wctob ; replaced, CRT version may sign-extend its return value
 wctomb
 wctomb_s
 wprintf
diff --git a/mingw-w64-crt/lib64/msvcr100.def.in b/mingw-w64-crt/lib64/msvcr100.def.in
index 24698cc..58d757b 100644
--- a/mingw-w64-crt/lib64/msvcr100.def.in
+++ b/mingw-w64-crt/lib64/msvcr100.def.in
@@ -1612,7 +1612,7 @@
 atol
 bsearch
 bsearch_s
-; btowc ; use replacement
+; btowc ; replaced for consistency with wctob
 calloc
 ceil DATA
 ceilf DATA
@@ -1854,7 +1854,7 @@
 wcstombs_s
 wcstoul
 wcsxfrm
-; wctob ; use replacement
+; wctob ; replaced, CRT version may sign-extend its return value
 wctomb
 wctomb_s
 wmemcpy_s
diff --git a/mingw-w64-crt/lib64/msvcr100d.def.in b/mingw-w64-crt/lib64/msvcr100d.def.in
index e3c7e1b..ff7662c 100644
--- a/mingw-w64-crt/lib64/msvcr100d.def.in
+++ b/mingw-w64-crt/lib64/msvcr100d.def.in
@@ -1677,7 +1677,7 @@
 atol
 bsearch
 bsearch_s
-; btowc ; use replacement
+; btowc ; replaced for consistency with wctob
 calloc
 ceil DATA ; overwritten
 ceilf DATA ; overwritten
@@ -1919,7 +1919,7 @@
 wcstombs_s
 wcstoul
 wcsxfrm
-; wctob ; use replacement
+; wctob ; replaced, CRT version may sign-extend its return value
 wctomb
 wctomb_s
 wmemcpy_s
diff --git a/mingw-w64-crt/lib64/msvcr110.def.in b/mingw-w64-crt/lib64/msvcr110.def.in
index 8ef9f86..4b3374c 100644
--- a/mingw-w64-crt/lib64/msvcr110.def.in
+++ b/mingw-w64-crt/lib64/msvcr110.def.in
@@ -1736,7 +1736,7 @@
 atol
 bsearch
 bsearch_s
-; btowc ; use replacement
+; btowc ; replaced for consistency with wctob
 calloc
 ceil
 ceilf
@@ -1978,7 +1978,7 @@
 wcstombs_s
 wcstoul
 wcsxfrm
-; wctob ; use replacement
+; wctob ; replaced, CRT version may sign-extend its return value
 wctomb
 wctomb_s
 wmemcpy_s
diff --git a/mingw-w64-crt/lib64/msvcr110d.def.in b/mingw-w64-crt/lib64/msvcr110d.def.in
index ad13f3a..792a504 100644
--- a/mingw-w64-crt/lib64/msvcr110d.def.in
+++ b/mingw-w64-crt/lib64/msvcr110d.def.in
@@ -1801,7 +1801,7 @@
 atol
 bsearch
 bsearch_s
-; btowc ; use replacement
+; btowc ; replaced for consistency with wctob
 calloc
 ceil
 ceilf
@@ -2043,7 +2043,7 @@
 wcstombs_s
 wcstoul
 wcsxfrm
-; wctob ; use replacement
+; wctob ; replaced, CRT version may sign-extend its return value
 wctomb
 wctomb_s
 wmemcpy_s
diff --git a/mingw-w64-crt/lib64/msvcr120.def.in b/mingw-w64-crt/lib64/msvcr120.def.in
index 0401dbf..caa8aac 100644
--- a/mingw-w64-crt/lib64/msvcr120.def.in
+++ b/mingw-w64-crt/lib64/msvcr120.def.in
@@ -1793,7 +1793,7 @@
 atoll
 bsearch
 bsearch_s
-; btowc ; use replacement
+; btowc ; replaced for consistency with wctob
 cabs
 cabsf
 ; cabsl ; Can't use long double functions from the CRT on x86
@@ -2240,7 +2240,7 @@
 wcstoull
 wcstoumax
 wcsxfrm
-; wctob ; use replacement
+; wctob ; replaced, CRT version may sign-extend its return value
 wctomb
 wctomb_s
 wctrans
diff --git a/mingw-w64-crt/lib64/msvcr120d.def.in b/mingw-w64-crt/lib64/msvcr120d.def.in
index bf914c7..8df009d 100644
--- a/mingw-w64-crt/lib64/msvcr120d.def.in
+++ b/mingw-w64-crt/lib64/msvcr120d.def.in
@@ -1858,7 +1858,7 @@
 atoll
 bsearch
 bsearch_s
-; btowc ; use replacement
+; btowc ; replaced for consistency with wctob
 cabs
 cabsf
 ; cabsl ; Can't use long double functions from the CRT on x86
@@ -2305,7 +2305,7 @@
 wcstoull
 wcstoumax
 wcsxfrm
-; wctob ; use replacement
+; wctob ; replaced, CRT version may sign-extend its return value
 wctomb
 wctomb_s
 wctrans
diff --git a/mingw-w64-crt/lib64/msvcr80.def.in b/mingw-w64-crt/lib64/msvcr80.def.in
index aaefaa6..affa2c8 100644
--- a/mingw-w64-crt/lib64/msvcr80.def.in
+++ b/mingw-w64-crt/lib64/msvcr80.def.in
@@ -1235,7 +1235,7 @@
 atol
 bsearch
 bsearch_s
-; btowc ; use replacement
+; btowc ; replaced for consistency with wctob
 calloc
 ceil DATA
 ceilf DATA
@@ -1474,7 +1474,7 @@
 wcstombs_s
 wcstoul
 wcsxfrm
-; wctob ; use replacement
+; wctob ; replaced, CRT version may sign-extend its return value
 wctomb
 wctomb_s
 wprintf
diff --git a/mingw-w64-crt/lib64/msvcr80d.def.in b/mingw-w64-crt/lib64/msvcr80d.def.in
index 5888e92..8c5da27 100644
--- a/mingw-w64-crt/lib64/msvcr80d.def.in
+++ b/mingw-w64-crt/lib64/msvcr80d.def.in
@@ -1312,7 +1312,7 @@
 atol
 bsearch
 bsearch_s
-; btowc ; use replacement
+; btowc ; replaced for consistency with wctob
 calloc
 ceil DATA ; overwritten
 ceilf DATA ; overwritten
@@ -1551,7 +1551,7 @@
 wcstombs_s
 wcstoul
 wcsxfrm
-; wctob ; use replacement
+; wctob ; replaced, CRT version may sign-extend its return value
 wctomb
 wctomb_s
 wprintf
diff --git a/mingw-w64-crt/lib64/msvcr90.def.in b/mingw-w64-crt/lib64/msvcr90.def.in
index c3524ff..ba66406 100644
--- a/mingw-w64-crt/lib64/msvcr90.def.in
+++ b/mingw-w64-crt/lib64/msvcr90.def.in
@@ -1232,7 +1232,7 @@
 atol
 bsearch
 bsearch_s
-; btowc ; use replacement
+; btowc ; replaced for consistency with wctob
 calloc
 ceil DATA
 ceilf DATA
@@ -1472,7 +1472,7 @@
 wcstombs_s
 wcstoul
 wcsxfrm
-; wctob ; use replacement
+; wctob ; replaced, CRT version may sign-extend its return value
 wctomb
 wctomb_s
 wprintf
diff --git a/mingw-w64-crt/lib64/msvcr90d.def.in b/mingw-w64-crt/lib64/msvcr90d.def.in
index e88cffa..c4f5688 100644
--- a/mingw-w64-crt/lib64/msvcr90d.def.in
+++ b/mingw-w64-crt/lib64/msvcr90d.def.in
@@ -1298,7 +1298,7 @@
 atol
 bsearch
 bsearch_s
-; btowc ; use replacement
+; btowc ; replaced for consistency with wctob
 calloc
 ceil DATA
 ceilf DATA
@@ -1538,7 +1538,7 @@
 wcstombs_s
 wcstoul
 wcsxfrm
-; wctob ; use replacement
+; wctob ; replaced, CRT version may sign-extend its return value
 wctomb
 wctomb_s
 wprintf
diff --git a/mingw-w64-crt/libarm32/msvcr110.def.in b/mingw-w64-crt/libarm32/msvcr110.def.in
index bba35f0..a8b580d 100644
--- a/mingw-w64-crt/libarm32/msvcr110.def.in
+++ b/mingw-w64-crt/libarm32/msvcr110.def.in
@@ -1722,7 +1722,7 @@
 atol
 bsearch
 bsearch_s
-; btowc ; use replacement
+; btowc ; replaced for consistency with wctob
 calloc
 ceil
 ceilf
@@ -1965,7 +1965,7 @@
 wcstombs_s
 wcstoul
 wcsxfrm
-; wctob ; use replacement
+; wctob ; replaced, CRT version may sign-extend its return value
 wctomb
 wctomb_s
 wmemcpy_s
diff --git a/mingw-w64-crt/libarm32/msvcr110d.def.in b/mingw-w64-crt/libarm32/msvcr110d.def.in
index 4ef8581..b0a5f5c 100644
--- a/mingw-w64-crt/libarm32/msvcr110d.def.in
+++ b/mingw-w64-crt/libarm32/msvcr110d.def.in
@@ -1787,7 +1787,7 @@
 atol
 bsearch
 bsearch_s
-; btowc ; use replacement
+; btowc ; replaced for consistency with wctob
 calloc
 ceil
 ceilf
@@ -2030,7 +2030,7 @@
 wcstombs_s
 wcstoul
 wcsxfrm
-; wctob ; use replacement
+; wctob ; replaced, CRT version may sign-extend its return value
 wctomb
 wctomb_s
 wmemcpy_s
diff --git a/mingw-w64-crt/libarm32/msvcr120.def.in b/mingw-w64-crt/libarm32/msvcr120.def.in
index 32c423f..746913c 100644
--- a/mingw-w64-crt/libarm32/msvcr120.def.in
+++ b/mingw-w64-crt/libarm32/msvcr120.def.in
@@ -1760,7 +1760,7 @@
 atoll
 bsearch
 bsearch_s
-; btowc ; use replacement
+; btowc ; replaced for consistency with wctob
 cabs
 cabsf
 cabsl
@@ -2208,7 +2208,7 @@
 wcstoull
 wcstoumax
 wcsxfrm
-; wctob ; use replacement
+; wctob ; replaced, CRT version may sign-extend its return value
 wctomb
 wctomb_s
 wctrans
diff --git a/mingw-w64-crt/libarm32/msvcr120d.def.in b/mingw-w64-crt/libarm32/msvcr120d.def.in
index 84faada..0473b44 100644
--- a/mingw-w64-crt/libarm32/msvcr120d.def.in
+++ b/mingw-w64-crt/libarm32/msvcr120d.def.in
@@ -1825,7 +1825,7 @@
 atoll
 bsearch
 bsearch_s
-; btowc ; use replacement
+; btowc ; replaced for consistency with wctob
 cabs
 cabsf
 cabsl
@@ -2273,7 +2273,7 @@
 wcstoull
 wcstoumax
 wcsxfrm
-; wctob ; use replacement
+; wctob ; replaced, CRT version may sign-extend its return value
 wctomb
 wctomb_s
 wctrans