diff --git a/NEWS b/NEWS
index 98d4b24ab4..4d52ccfaa0 100644
--- a/NEWS
+++ b/NEWS
@@ -38,6 +38,7 @@ The following bugs are resolved with this release:
   [26932] libc: sh: Multiple floating point functions defined as stubs only
   [27130] "rep movsb" performance issue
   [27177] GLIBC_TUNABLES=glibc.cpu.x86_ibt=on:glibc.cpu.x86_shstk=on doesn't work
+  [28524] Conversion from ISO-2022-JP-3 with iconv may emit spurious NULs
 
 Security related changes:
 
diff --git a/iconvdata/Makefile b/iconvdata/Makefile
index 72a91416d3..8fbb67a52b 100644
--- a/iconvdata/Makefile
+++ b/iconvdata/Makefile
@@ -1,4 +1,5 @@
 # Copyright (C) 1997-2020 Free Software Foundation, Inc.
+# Copyright (C) The GNU Toolchain Authors.
 # This file is part of the GNU C Library.
 
 # The GNU C Library is free software; you can redistribute it and/or
@@ -73,7 +74,8 @@ modules.so := $(addsuffix .so, $(modules))
 ifeq (yes,$(build-shared))
 tests = bug-iconv1 bug-iconv2 tst-loading tst-e2big tst-iconv4 bug-iconv4 \
 	tst-iconv6 bug-iconv5 bug-iconv6 tst-iconv7 bug-iconv8 bug-iconv9 \
-	bug-iconv10 bug-iconv11 bug-iconv12 bug-iconv13 bug-iconv14
+	bug-iconv10 bug-iconv11 bug-iconv12 bug-iconv13 bug-iconv14 \
+	bug-iconv15
 ifeq ($(have-thread-library),yes)
 tests += bug-iconv3
 endif
@@ -318,6 +320,8 @@ $(objpfx)bug-iconv12.out: $(objpfx)gconv-modules \
 			  $(addprefix $(objpfx),$(modules.so))
 $(objpfx)bug-iconv14.out: $(objpfx)gconv-modules \
 			  $(addprefix $(objpfx),$(modules.so))
+$(objpfx)bug-iconv15.out: $(addprefix $(objpfx), $(gconv-modules)) \
+			  $(addprefix $(objpfx),$(modules.so))
 
 $(objpfx)iconv-test.out: run-iconv-test.sh $(objpfx)gconv-modules \
 			 $(addprefix $(objpfx),$(modules.so)) \
diff --git a/iconvdata/bug-iconv15.c b/iconvdata/bug-iconv15.c
new file mode 100644
index 0000000000..cc04bd0313
--- /dev/null
+++ b/iconvdata/bug-iconv15.c
@@ -0,0 +1,60 @@
+/* Bug 28524: Conversion from ISO-2022-JP-3 with iconv
+   may emit spurious NUL character on state reset.
+   Copyright (C) The GNU Toolchain Authors.
+   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 <stddef.h>
+#include <iconv.h>
+#include <support/check.h>
+
+static int
+do_test (void)
+{
+  char in[] = "\x1b(I";
+  char *inbuf = in;
+  size_t inleft = sizeof (in) - 1;
+  char out[1];
+  char *outbuf = out;
+  size_t outleft = sizeof (out);
+  iconv_t cd;
+
+  cd = iconv_open ("UTF8", "ISO-2022-JP-3");
+  TEST_VERIFY_EXIT (cd != (iconv_t) -1);
+
+  /* First call to iconv should alter internal state.
+     Now, JISX0201_Kana_set is selected and
+     state value != ASCII_set.  */
+  TEST_VERIFY (iconv (cd, &inbuf, &inleft, &outbuf, &outleft) != (size_t) -1);
+
+  /* No bytes should have been added to
+     the output buffer at this point.  */
+  TEST_VERIFY (outbuf == out);
+  TEST_VERIFY (outleft == sizeof (out));
+
+  /* Second call shall emit spurious NUL character in unpatched glibc.  */
+  TEST_VERIFY (iconv (cd, NULL, NULL, &outbuf, &outleft) != (size_t) -1);
+
+  /* No characters are expected to be produced.  */
+  TEST_VERIFY (outbuf == out);
+  TEST_VERIFY (outleft == sizeof (out));
+
+  TEST_VERIFY_EXIT (iconv_close (cd) != -1);
+
+  return 0;
+}
+
+#include <support/test-driver.c>
diff --git a/iconvdata/iso-2022-jp-3.c b/iconvdata/iso-2022-jp-3.c
index 62cbc54a11..c7b470db61 100644
--- a/iconvdata/iso-2022-jp-3.c
+++ b/iconvdata/iso-2022-jp-3.c
@@ -1,5 +1,6 @@
 /* Conversion module for ISO-2022-JP-3.
    Copyright (C) 1998-2020 Free Software Foundation, Inc.
+   Copyright (C) The GNU Toolchain Authors.
    This file is part of the GNU C Library.
    Contributed by Ulrich Drepper <drepper@cygnus.com>, 1998,
    and Bruno Haible <bruno@clisp.org>, 2002.
@@ -81,20 +82,31 @@ enum
    the output state to the initial state.  This has to be done during the
    flushing.  */
 #define EMIT_SHIFT_TO_INIT \
-  if (data->__statep->__count != ASCII_set)			      \
+  if ((data->__statep->__count & ~7) != ASCII_set)			      \
     {									      \
       if (FROM_DIRECTION)						      \
 	{								      \
-	  if (__glibc_likely (outbuf + 4 <= outend))			      \
+	  uint32_t ch = data->__statep->__count >> 6;			      \
+									      \
+	  if (__glibc_unlikely (ch != 0))				      \
 	    {								      \
-	      /* Write out the last character.  */			      \
-	      *((uint32_t *) outbuf) = data->__statep->__count >> 6;	      \
-	      outbuf += sizeof (uint32_t);				      \
-	      data->__statep->__count = ASCII_set;			\
+	      if (__glibc_likely (outbuf + 4 <= outend))		      \
+		{							      \
+		  /* Write out the last character.  */			      \
+		  put32u (outbuf, ch);					      \
+		  outbuf += 4;						      \
+		  data->__statep->__count &= 7;				      \
+		  data->__statep->__count |= ASCII_set;			      \
+		}							      \
+	      else							      \
+		/* We don't have enough room in the output buffer.  */	      \
+		status = __GCONV_FULL_OUTPUT;				      \
 	    }								      \
 	  else								      \
-	    /* We don't have enough room in the output buffer.  */	      \
-	    status = __GCONV_FULL_OUTPUT;				      \
+	    {								      \
+	      data->__statep->__count &= 7;				      \
+	      data->__statep->__count |= ASCII_set;			      \
+	    }								      \
 	}								      \
       else								      \
 	{								      \