diff --git a/localedata/Makefile b/localedata/Makefile
index 5d2ebd0256..01b32348d4 100644
--- a/localedata/Makefile
+++ b/localedata/Makefile
@@ -236,6 +236,7 @@ tests = \
   bug-iconv-trans \
   bug-setlocale1 \
   bug-usesetlocale \
+  tst-bz12701-lc \
   tst-bz13988 \
   tst-c-utf8-consistency \
   tst-digits \
diff --git a/localedata/tst-bz12701-lc.c b/localedata/tst-bz12701-lc.c
new file mode 100644
index 0000000000..fcc9f29a14
--- /dev/null
+++ b/localedata/tst-bz12701-lc.c
@@ -0,0 +1,224 @@
+/* Verify scanf field width handling with the 'lc' conversion (BZ #12701).
+   Copyright (C) 2025 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <https://www.gnu.org/licenses/>.  */
+
+#include <locale.h>
+#include <stddef.h>
+#include <stdio.h>
+#include <string.h>
+#include <wchar.h>
+
+#include <libc-diag.h>
+#include <support/check.h>
+#include <support/next_to_fault.h>
+#include <support/xstdio.h>
+
+/* Compare character-wise the initial part of the wide character object
+   pointed to by WS corresponding to wide characters obtained by the
+   conversion of first N bytes of the multibyte character object pointed
+   to by S.  */
+
+static int
+tst_bz12701_lc_memcmp (const wchar_t *ds, const char *s, size_t n)
+{
+  size_t nc = mbsnrtowcs (NULL, &s, n, 0, NULL);
+
+  struct support_next_to_fault ntf;
+  ntf = support_next_to_fault_allocate (nc * sizeof (wchar_t));
+  wchar_t *ss = (wchar_t *) ntf.buffer;
+
+  mbsnrtowcs (ss, &s, n, nc, NULL);
+  int r = wmemcmp (ds, ss, nc);
+
+  support_next_to_fault_free (&ntf);
+
+  return r;
+}
+
+/* Verify various aspects of field width handling, including the data
+   obtained, the number of bytes consumed, and the stream position.  */
+
+static int
+do_test (void)
+{
+  if (setlocale (LC_ALL, "pl_PL.UTF-8") == NULL)
+    FAIL_EXIT1 ("setlocale (LC_ALL, \"pl_PL.UTF-8\")");
+
+  /* Part of a tongue-twister in Polish, which says:
+     "On a rainy morning cuckoos and warblers, rather than starting
+     on earthworms, stuffed themselves fasted with the flesh of cress."  */
+  static const char s[126] = "Dżdżystym rankiem gżegżółki i piegże, "
+			     "zamiast wziąć się za dżdżownice, "
+			     "nażarły się na czczo miąższu rzeżuchy";
+
+  const char *sp = s;
+  size_t nc;
+  TEST_VERIFY_EXIT ((nc = mbsnrtowcs (NULL, &sp, sizeof (s), 0, NULL)) == 108);
+
+  struct support_next_to_fault ntfo, ntfi;
+  ntfo = support_next_to_fault_allocate (nc * sizeof (wchar_t));
+  ntfi = support_next_to_fault_allocate (sizeof (s));
+  wchar_t *e = (wchar_t *) ntfo.buffer + nc;
+  char *b = ntfi.buffer;
+
+  wchar_t *c;
+  FILE *f;
+  int ic;
+  int n;
+  int i;
+
+  memcpy (ntfi.buffer, s, sizeof (s));
+
+  ic = i = 0;
+  f = fmemopen (b, sizeof (s), "r");
+  if (f == NULL)
+    FAIL_EXIT1 ("fmemopen: %m");
+
+  c = e - 1;
+  TEST_VERIFY_EXIT (ftell (f) == i);
+  /* Avoid: "warning: zero width in gnu_scanf format [-Werror=format=]".  */
+  DIAG_PUSH_NEEDS_COMMENT;
+  DIAG_IGNORE_NEEDS_COMMENT (4.9, "-Wformat");
+  TEST_VERIFY_EXIT (fscanf (f, "%0lc%n", c, &n) == 1);
+  DIAG_POP_NEEDS_COMMENT;
+  TEST_VERIFY_EXIT (n == 1);
+  TEST_VERIFY_EXIT (tst_bz12701_lc_memcmp (c, s + i, n) == 0);
+  ic += 1;
+  i += n;
+
+  c = e - 1;
+  TEST_VERIFY_EXIT (ftell (f) == i);
+  TEST_VERIFY_EXIT (fscanf (f, "%lc%n", c, &n) == 1);
+  TEST_VERIFY_EXIT (n == 2);
+  TEST_VERIFY_EXIT (tst_bz12701_lc_memcmp (c, s + i, n) == 0);
+  ic += 1;
+  i += n;
+
+  c = e - 1;
+  TEST_VERIFY_EXIT (ftell (f) == i);
+  TEST_VERIFY_EXIT (fscanf (f, "%1lc%n", c, &n) == 1);
+  TEST_VERIFY_EXIT (n == 1);
+  TEST_VERIFY_EXIT (tst_bz12701_lc_memcmp (c, s + i, n) == 0);
+  ic += 1;
+  i += n;
+
+  c = e - 2;
+  TEST_VERIFY_EXIT (ftell (f) == i);
+  TEST_VERIFY_EXIT (fscanf (f, "%2lc%n", c, &n) == 1);
+  TEST_VERIFY_EXIT (n == 3);
+  TEST_VERIFY_EXIT (tst_bz12701_lc_memcmp (c, s + i, n) == 0);
+  ic += 2;
+  i += n;
+
+  c = e - 4;
+  TEST_VERIFY_EXIT (ftell (f) == i);
+  TEST_VERIFY_EXIT (fscanf (f, "%4lc%n", c, &n) == 1);
+  TEST_VERIFY_EXIT (n == 4);
+  TEST_VERIFY_EXIT (tst_bz12701_lc_memcmp (c, s + i, n) == 0);
+  ic += 4;
+  i += n;
+
+  c = e - 8;
+  TEST_VERIFY_EXIT (ftell (f) == i);
+  TEST_VERIFY_EXIT (fscanf (f, "%8lc%n", c, &n) == 1);
+  TEST_VERIFY_EXIT (n == 8);
+  TEST_VERIFY_EXIT (tst_bz12701_lc_memcmp (c, s + i, n) == 0);
+  ic += 8;
+  i += n;
+
+  c = e - 16;
+  TEST_VERIFY_EXIT (ftell (f) == i);
+  TEST_VERIFY_EXIT (fscanf (f, "%16lc%n", c, &n) == 1);
+  TEST_VERIFY_EXIT (n == 20);
+  TEST_VERIFY_EXIT (tst_bz12701_lc_memcmp (c, s + i, n) == 0);
+  ic += 16;
+  i += n;
+
+  c = e - 32;
+  TEST_VERIFY_EXIT (ftell (f) == i);
+  TEST_VERIFY_EXIT (fscanf (f, "%32lc%n", c, &n) == 1);
+  TEST_VERIFY_EXIT (n == 38);
+  TEST_VERIFY_EXIT (tst_bz12701_lc_memcmp (c, s + i, n) == 0);
+  ic += 32;
+  i += n;
+
+  c = e - (nc - ic);
+  TEST_VERIFY_EXIT (ftell (f) == i);
+  TEST_VERIFY_EXIT (fscanf (f, "%64lc%n", c, &n) == EOF);
+  TEST_VERIFY_EXIT (n == 38);
+  TEST_VERIFY_EXIT (tst_bz12701_lc_memcmp (c, s + i, sizeof (s) - i) == 0);
+
+  TEST_VERIFY_EXIT (ftell (f) == sizeof (s));
+  TEST_VERIFY_EXIT (feof (f) != 0);
+
+  xfclose (f);
+
+  ic = i = 0;
+  f = fmemopen (b, 3, "r");
+  if (f == NULL)
+    FAIL_EXIT1 ("fmemopen: %m");
+
+  c = e - 2;
+  TEST_VERIFY_EXIT (ftell (f) == i);
+  TEST_VERIFY_EXIT (fscanf (f, "%2lc%n", c, &n) == 1);
+  TEST_VERIFY_EXIT (n == 3);
+  TEST_VERIFY_EXIT (tst_bz12701_lc_memcmp (c, s + i, n) == 0);
+  ic += 2;
+  i += n;
+
+  c = e - (nc - ic);
+  TEST_VERIFY_EXIT (feof (f) == 0);
+  TEST_VERIFY_EXIT (ftell (f) == i);
+  TEST_VERIFY_EXIT (fscanf (f, "%2lc%n", c, &n) == EOF);
+  TEST_VERIFY_EXIT (n == 3);
+
+  TEST_VERIFY_EXIT (ftell (f) == 3);
+  TEST_VERIFY_EXIT (feof (f) != 0);
+
+  xfclose (f);
+
+  ic = i = 0;
+  f = fmemopen (b, 3, "r");
+  if (f == NULL)
+    FAIL_EXIT1 ("fmemopen: %m");
+
+  c = e - 1;
+  TEST_VERIFY_EXIT (ftell (f) == i);
+  TEST_VERIFY_EXIT (fscanf (f, "%lc%n", c, &n) == 1);
+  TEST_VERIFY_EXIT (n == 1);
+  TEST_VERIFY_EXIT (tst_bz12701_lc_memcmp (c, s + i, n) == 0);
+  ic += 1;
+  i += n;
+
+  c = e - (nc - ic);
+  TEST_VERIFY_EXIT (ftell (f) == i);
+  TEST_VERIFY_EXIT (fscanf (f, "%2lc%n", c, &n) == EOF);
+  TEST_VERIFY_EXIT (n == 1);
+  TEST_VERIFY_EXIT (tst_bz12701_lc_memcmp (c, s + i, 3 - i) == 0);
+
+  TEST_VERIFY_EXIT (ftell (f) == 3);
+  TEST_VERIFY_EXIT (feof (f) != 0);
+
+  xfclose (f);
+
+  support_next_to_fault_free (&ntfi);
+  support_next_to_fault_free (&ntfo);
+
+  return 0;
+}
+
+#include <support/test-driver.c>
diff --git a/stdio-common/Makefile b/stdio-common/Makefile
index ae2b90c2ad..8da164695f 100644
--- a/stdio-common/Makefile
+++ b/stdio-common/Makefile
@@ -260,6 +260,7 @@ tests := \
   tllformat \
   tst-bz11319 \
   tst-bz11319-fortify2 \
+  tst-bz12701-c \
   tst-cookie \
   tst-dprintf-length \
   tst-fclose-devzero \
diff --git a/stdio-common/tst-bz12701-c.c b/stdio-common/tst-bz12701-c.c
new file mode 100644
index 0000000000..ffb4330bfb
--- /dev/null
+++ b/stdio-common/tst-bz12701-c.c
@@ -0,0 +1,175 @@
+/* Verify scanf field width handling with the 'c' conversion (BZ #12701).
+   Copyright (C) 2025 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <https://www.gnu.org/licenses/>.  */
+
+#include <stdio.h>
+#include <string.h>
+
+#include <libc-diag.h>
+#include <support/check.h>
+#include <support/next_to_fault.h>
+#include <support/xstdio.h>
+
+/* Verify various aspects of field width handling, including the data
+   obtained, the number of bytes consumed, and the stream position.  */
+
+static int
+do_test (void)
+{
+  static const char s[43] = "The quick brown fox jumps over the lazy dog";
+  struct support_next_to_fault ntfo, ntfi;
+  ntfo = support_next_to_fault_allocate (sizeof (s));
+  ntfi = support_next_to_fault_allocate (sizeof (s));
+  char *e = ntfo.buffer + sizeof (s);
+  char *b = ntfi.buffer;
+
+  char *c;
+  FILE *f;
+  int n;
+  int i;
+
+  memcpy (ntfi.buffer, s, sizeof (s));
+
+  i = 0;
+  f = fmemopen (b, sizeof (s), "r");
+  if (f == NULL)
+    FAIL_EXIT1 ("fmemopen: %m");
+
+  c = e - 1;
+  TEST_VERIFY_EXIT (ftell (f) == i);
+  /* Avoid: "warning: zero width in gnu_scanf format [-Werror=format=]".  */
+  DIAG_PUSH_NEEDS_COMMENT;
+  DIAG_IGNORE_NEEDS_COMMENT (4.9, "-Wformat");
+  TEST_VERIFY_EXIT (fscanf (f, "%0c%n", c, &n) == 1);
+  DIAG_POP_NEEDS_COMMENT;
+  TEST_VERIFY_EXIT (n == 1);
+  TEST_VERIFY_EXIT (memcmp (c, s + i, n) == 0);
+  i += n;
+
+  c = e - 1;
+  TEST_VERIFY_EXIT (ftell (f) == i);
+  TEST_VERIFY_EXIT (fscanf (f, "%c%n", c, &n) == 1);
+  TEST_VERIFY_EXIT (n == 1);
+  TEST_VERIFY_EXIT (memcmp (c, s + i, n) == 0);
+  i += n;
+
+  c = e - 1;
+  TEST_VERIFY_EXIT (ftell (f) == i);
+  TEST_VERIFY_EXIT (fscanf (f, "%1c%n", c, &n) == 1);
+  TEST_VERIFY_EXIT (n == 1);
+  TEST_VERIFY_EXIT (memcmp (c, s + i, n) == 0);
+  i += n;
+
+  c = e - 2;
+  TEST_VERIFY_EXIT (ftell (f) == i);
+  TEST_VERIFY_EXIT (fscanf (f, "%2c%n", c, &n) == 1);
+  TEST_VERIFY_EXIT (n == 2);
+  TEST_VERIFY_EXIT (memcmp (c, s + i, n) == 0);
+  i += n;
+
+  c = e - 4;
+  TEST_VERIFY_EXIT (ftell (f) == i);
+  TEST_VERIFY_EXIT (fscanf (f, "%4c%n", c, &n) == 1);
+  TEST_VERIFY_EXIT (n == 4);
+  TEST_VERIFY_EXIT (memcmp (c, s + i, n) == 0);
+  i += n;
+
+  c = e - 8;
+  TEST_VERIFY_EXIT (ftell (f) == i);
+  TEST_VERIFY_EXIT (fscanf (f, "%8c%n", c, &n) == 1);
+  TEST_VERIFY_EXIT (n == 8);
+  TEST_VERIFY_EXIT (memcmp (c, s + i, n) == 0);
+  i += n;
+
+  c = e - 16;
+  TEST_VERIFY_EXIT (ftell (f) == i);
+  TEST_VERIFY_EXIT (fscanf (f, "%16c%n", c, &n) == 1);
+  TEST_VERIFY_EXIT (n == 16);
+  TEST_VERIFY_EXIT (memcmp (c, s + i, n) == 0);
+  i += n;
+
+  c = e - (sizeof (s) - i);
+  TEST_VERIFY_EXIT (ftell (f) == i);
+  TEST_VERIFY_EXIT (fscanf (f, "%32c%n", c, &n) == EOF);
+  TEST_VERIFY_EXIT (n == 16);
+  TEST_VERIFY_EXIT (memcmp (c, s + i, sizeof (s) - i) == 0);
+
+  TEST_VERIFY_EXIT (ftell (f) == sizeof (s));
+  TEST_VERIFY_EXIT (feof (f) != 0);
+
+  xfclose (f);
+
+  i = 0;
+  f = fmemopen (b, 3, "r");
+  if (f == NULL)
+    FAIL_EXIT1 ("fmemopen: %m");
+
+  c = e - 1;
+  TEST_VERIFY_EXIT (ftell (f) == i);
+  TEST_VERIFY_EXIT (fscanf (f, "%c%n", c, &n) == 1);
+  TEST_VERIFY_EXIT (n == 1);
+  TEST_VERIFY_EXIT (memcmp (c, s + i, n) == 0);
+  i += n;
+
+  c = e - 2;
+  TEST_VERIFY_EXIT (ftell (f) == i);
+  TEST_VERIFY_EXIT (fscanf (f, "%2c%n", c, &n) == 1);
+  TEST_VERIFY_EXIT (n == 2);
+  TEST_VERIFY_EXIT (memcmp (c, s + i, n) == 0);
+  i += n;
+
+  c = e - (3 - i);
+  TEST_VERIFY_EXIT (feof (f) == 0);
+  TEST_VERIFY_EXIT (ftell (f) == i);
+  TEST_VERIFY_EXIT (fscanf (f, "%2c%n", c, &n) == EOF);
+  TEST_VERIFY_EXIT (n == 2);
+
+  TEST_VERIFY_EXIT (ftell (f) == i);
+  TEST_VERIFY_EXIT (feof (f) != 0);
+
+  xfclose (f);
+
+  i = 0;
+  f = fmemopen (b, 3, "r");
+  if (f == NULL)
+    FAIL_EXIT1 ("fmemopen: %m");
+
+  c = e - 2;
+  TEST_VERIFY_EXIT (ftell (f) == i);
+  TEST_VERIFY_EXIT (fscanf (f, "%2c%n", c, &n) == 1);
+  TEST_VERIFY_EXIT (n == 2);
+  TEST_VERIFY_EXIT (memcmp (c, s + i, n) == 0);
+  i += n;
+
+  c = e - (3 - i);
+  TEST_VERIFY_EXIT (ftell (f) == i);
+  TEST_VERIFY_EXIT (fscanf (f, "%2c%n", c, &n) == EOF);
+  TEST_VERIFY_EXIT (n == 2);
+  TEST_VERIFY_EXIT (memcmp (c, s + i, 3 - i) == 0);
+
+  TEST_VERIFY_EXIT (ftell (f) == 3);
+  TEST_VERIFY_EXIT (feof (f) != 0);
+
+  xfclose (f);
+
+  support_next_to_fault_free (&ntfi);
+  support_next_to_fault_free (&ntfo);
+
+  return 0;
+}
+
+#include <support/test-driver.c>
diff --git a/stdio-common/tst-scanf-format-c-c.input b/stdio-common/tst-scanf-format-c-c.input
index a3a6ee26af..67c78651ba 100644
--- a/stdio-common/tst-scanf-format-c-c.input
+++ b/stdio-common/tst-scanf-format-c-c.input
@@ -22,30 +22,14 @@
 %*2c:brown fox:0:2:
 %2c:jumps over the lazy dog:1:2:ju:
 %*2c:jumps over the lazy dog:0:2:
-# BZ12701 %5c:The:0:-1:
-# BZ12701 %*5c:The:0:-1:
 %5c:quick:1:5:quick:
 %*5c:quick:0:5:
 %5c:brown fox:1:5:brown:
 %*5c:brown fox:0:5:
 %5c:jumps over the lazy dog:1:5:jumps:
 %*5c:jumps over the lazy dog:0:5:
-# BZ12701 %10c:The:0:-1:
-# BZ12701 %*10c:The:0:-1:
-# BZ12701 %10c:quick:0:-1:
-# BZ12701 %*10c:quick:0:-1:
-# BZ12701 %10c:brown fox:0:-1:
-# BZ12701 %*10c:brown fox:0:-1:
 %10c:jumps over the lazy dog:1:10:jumps over:
 %*10c:jumps over the lazy dog:0:10:
-# BZ12701 %25c:The:0:-1:
-# BZ12701 %*25c:The:0:-1:
-# BZ12701 %25c:quick:0:-1:
-# BZ12701 %*25c:quick:0:-1:
-# BZ12701 %25c:brown fox:0:-1:
-# BZ12701 %*25c:brown fox:0:-1:
-# BZ12701 %25c:jumps over the lazy dog:0:-1:
-# BZ12701 %*25c:jumps over the lazy dog:0:-1:
 %5c: The :1:5: The :
 %*5c: The :0:5:
 %5c: quick :1:5: quic:
@@ -54,11 +38,5 @@
 %*5c: brown fox :0:5:
 %5c: jumps over the lazy dog :1:5: jump:
 %*5c: jumps over the lazy dog :0:5:
-# BZ12701 %25c: The :0:-1:
-# BZ12701 %*25c: The :0:-1:
-# BZ12701 %25c: quick :0:-1:
-# BZ12701 %*25c: quick :0:-1:
-# BZ12701 %25c: brown fox :0:-1:
-# BZ12701 %*25c: brown fox :0:-1:
 %25c: jumps over the lazy dog :1:25: jumps over the lazy dog :
 %*25c: jumps over the lazy dog :0:25:
diff --git a/stdio-common/vfscanf-internal.c b/stdio-common/vfscanf-internal.c
index daeb068dda..d8facb6e89 100644
--- a/stdio-common/vfscanf-internal.c
+++ b/stdio-common/vfscanf-internal.c
@@ -898,6 +898,8 @@ __vfscanf_internal (FILE *s, const char *format, va_list argptr,
 	      else
 		while (--width > 0 && inchar () != EOF);
 #endif
+	      if (width > 0)
+		input_error ();
 
 	      if (!(flags & SUPPRESS))
 		{
@@ -1051,6 +1053,8 @@ __vfscanf_internal (FILE *s, const char *format, va_list argptr,
 	    while (--width > 0 && inchar () != EOF);
 	  }
 #endif
+	  if (width > 0)
+	    input_error ();
 
 	  if (!(flags & SUPPRESS))
 	    {