diff --git a/MANIFEST b/MANIFEST
index 302182f33..fcd66bfac 100644
--- a/MANIFEST
+++ b/MANIFEST
@@ -138,6 +138,7 @@ lib/util/dup3.c
 lib/util/event.c
 lib/util/event_poll.c
 lib/util/event_select.c
+lib/util/explicit_bzero.c
 lib/util/fatal.c
 lib/util/fchmodat.c
 lib/util/fnmatch.c
@@ -163,7 +164,6 @@ lib/util/locking.c
 lib/util/logfac.c
 lib/util/logpri.c
 lib/util/memrchr.c
-lib/util/memset_s.c
 lib/util/mkdir_parents.c
 lib/util/mksiglist.c
 lib/util/mksiglist.h
diff --git a/config.h.in b/config.h.in
index 1168b38db..c36333910 100644
--- a/config.h.in
+++ b/config.h.in
@@ -88,6 +88,9 @@
 /* Define to 1 to enable BSM audit support. */
 #undef HAVE_BSM_AUDIT
 
+/* Define to 1 if you have the `bzero' function. */
+#undef HAVE_BZERO
+
 /* Define to 1 if you have the `cfmakeraw' function. */
 #undef HAVE_CFMAKERAW
 
@@ -255,6 +258,12 @@
 /* Define to 1 if you have the `execvpe' function. */
 #undef HAVE_EXECVPE
 
+/* Define to 1 if you have the `explicit_bzero' function. */
+#undef HAVE_EXPLICIT_BZERO
+
+/* Define to 1 if you have the `explicit_memset' function. */
+#undef HAVE_EXPLICIT_MEMSET
+
 /* Define to 1 if you have the `faccessat' function. */
 #undef HAVE_FACCESSAT
 
@@ -535,6 +544,9 @@
 /* Define to 1 if you have the `memrchr' function. */
 #undef HAVE_MEMRCHR
 
+/* Define to 1 if you have the `memset_explicit' function. */
+#undef HAVE_MEMSET_EXPLICIT
+
 /* Define to 1 if you have the `memset_s' function. */
 #undef HAVE_MEMSET_S
 
@@ -1263,9 +1275,6 @@
 /* Define to empty if `const' does not conform to ANSI C. */
 #undef const
 
-/* Define to `int' if <sys/types.h> does not define. */
-#undef errno_t
-
 /* Define to `int' if <sys/types.h> doesn't define. */
 #undef gid_t
 
@@ -1284,9 +1293,6 @@
 /* Define to an OS-specific initialization function or `os_init_common'. */
 #undef os_init
 
-/* Define to `size_t' if <sys/types.h> does not define. */
-#undef rsize_t
-
 /* Define to `int' if <signal.h> does not define. */
 #undef sig_atomic_t
 
diff --git a/configure b/configure
index 1d1c19cee..8e3af5fd0 100755
--- a/configure
+++ b/configure
@@ -18057,8 +18057,6 @@ fi
 
 
 fi
-$as_echo "#define __STDC_WANT_LIB_EXT1__ 1" >>confdefs.h
-
 ac_fn_c_check_type "$LINENO" "mode_t" "ac_cv_type_mode_t" "$ac_includes_default"
 if test "x$ac_cv_type_mode_t" = xyes; then :
 
@@ -18318,28 +18316,6 @@ else
 
 fi
 
-ac_fn_c_check_type "$LINENO" "rsize_t" "ac_cv_type_rsize_t" "$ac_includes_default"
-if test "x$ac_cv_type_rsize_t" = xyes; then :
-
-else
-
-cat >>confdefs.h <<_ACEOF
-#define rsize_t size_t
-_ACEOF
-
-fi
-
-ac_fn_c_check_type "$LINENO" "errno_t" "ac_cv_type_errno_t" "$ac_includes_default"
-if test "x$ac_cv_type_errno_t" = xyes; then :
-
-else
-
-cat >>confdefs.h <<_ACEOF
-#define errno_t int
-_ACEOF
-
-fi
-
 
 { $as_echo "$as_me:${as_lineno-$LINENO}: checking max length of uid_t" >&5
 $as_echo_n "checking max length of uid_t... " >&6; }
@@ -20513,6 +20489,44 @@ fi
 done
 
 
+fi
+done
+
+for ac_func in explicit_bzero
+do :
+  ac_fn_c_check_func "$LINENO" "explicit_bzero" "ac_cv_func_explicit_bzero"
+if test "x$ac_cv_func_explicit_bzero" = xyes; then :
+  cat >>confdefs.h <<_ACEOF
+#define HAVE_EXPLICIT_BZERO 1
+_ACEOF
+
+else
+
+    case " $LIBOBJS " in
+  *" explicit_bzero.$ac_objext "* ) ;;
+  *) LIBOBJS="$LIBOBJS explicit_bzero.$ac_objext"
+ ;;
+esac
+
+
+    for _sym in sudo_explicit_bzero; do
+	COMPAT_EXP="${COMPAT_EXP}${_sym}
+"
+    done
+
+    for ac_func in explicit_memset memset_explicit memset_s bzero
+do :
+  as_ac_var=`$as_echo "ac_cv_func_$ac_func" | $as_tr_sh`
+ac_fn_c_check_func "$LINENO" "$ac_func" "$as_ac_var"
+if eval test \"x\$"$as_ac_var"\" = x"yes"; then :
+  cat >>confdefs.h <<_ACEOF
+#define `$as_echo "HAVE_$ac_func" | $as_tr_cpp` 1
+_ACEOF
+ break
+fi
+done
+
+
 fi
 done
 
@@ -20659,32 +20673,6 @@ esac
     done
 
 
-fi
-done
-
-for ac_func in memset_s
-do :
-  ac_fn_c_check_func "$LINENO" "memset_s" "ac_cv_func_memset_s"
-if test "x$ac_cv_func_memset_s" = xyes; then :
-  cat >>confdefs.h <<_ACEOF
-#define HAVE_MEMSET_S 1
-_ACEOF
-
-else
-
-    case " $LIBOBJS " in
-  *" memset_s.$ac_objext "* ) ;;
-  *) LIBOBJS="$LIBOBJS memset_s.$ac_objext"
- ;;
-esac
-
-
-    for _sym in sudo_memset_s; do
-	COMPAT_EXP="${COMPAT_EXP}${_sym}
-"
-    done
-
-
 fi
 done
 
diff --git a/configure.ac b/configure.ac
index faaa51f6a..3b3d047f3 100644
--- a/configure.ac
+++ b/configure.ac
@@ -2504,9 +2504,7 @@ if test ${with_project-'no'} != "no"; then
 fi
 dnl
 dnl typedef checks
-dnl We need to define __STDC_WANT_LIB_EXT1__ for errno_t and rsize_t
 dnl
-AC_DEFINE([__STDC_WANT_LIB_EXT1__])
 AC_TYPE_MODE_T
 AC_TYPE_UID_T
 AC_CHECK_TYPE([clockid_t], [], [AC_DEFINE(clockid_t, int)], [#include <sys/types.h>
@@ -2527,8 +2525,6 @@ AC_CHECK_TYPE(uint64_t, unsigned long long)
 AC_CHECK_TYPE(socklen_t, [], [AC_DEFINE(socklen_t, unsigned int)], [
 AC_INCLUDES_DEFAULT
 #include <sys/socket.h>])
-AC_CHECK_TYPE(rsize_t, size_t)
-AC_CHECK_TYPE(errno_t, int)
 SUDO_UID_T_LEN
 SUDO_SOCK_SA_LEN
 SUDO_SOCK_SIN_LEN
@@ -2810,6 +2806,11 @@ AC_CHECK_FUNCS([futimens], [], [
     SUDO_APPEND_COMPAT_EXP(sudo_futimens)
     AC_CHECK_FUNCS([futimes futimesat futime], [break])
 ])
+AC_CHECK_FUNCS([explicit_bzero], [], [
+    AC_LIBOBJ(explicit_bzero)
+    SUDO_APPEND_COMPAT_EXP(sudo_explicit_bzero)
+    AC_CHECK_FUNCS([explicit_memset memset_explicit memset_s bzero], [break])
+])
 SUDO_FUNC_FNMATCH([AC_DEFINE(HAVE_FNMATCH)], [
     AC_LIBOBJ(fnmatch)
     SUDO_APPEND_COMPAT_EXP(sudo_fnmatch)
@@ -2824,10 +2825,6 @@ AC_CHECK_FUNCS([memrchr], [], [
     AC_LIBOBJ(memrchr)
     SUDO_APPEND_COMPAT_EXP(sudo_memrchr)
 ])
-AC_CHECK_FUNCS([memset_s], [], [
-    AC_LIBOBJ(memset_s)
-    SUDO_APPEND_COMPAT_EXP(sudo_memset_s)
-])
 AC_CHECK_FUNCS(nanosleep, [], [
     # On Solaris, nanosleep is in librt
     AC_CHECK_LIB(rt, nanosleep, [
diff --git a/doc/sudo_plugin.man.in b/doc/sudo_plugin.man.in
index 0b69f4fb7..4ba139f49 100644
--- a/doc/sudo_plugin.man.in
+++ b/doc/sudo_plugin.man.in
@@ -4481,9 +4481,6 @@ the trailing NUL character).
 In practical terms, this is the longest password
 \fBsudo\fR
 will support.
-It is also useful as a maximum value for the
-\fBmemset_s\fR()
-function when clearing passwords filled in by the conversation function.
 .PP
 The
 \fBprintf\fR()-style
diff --git a/doc/sudo_plugin.mdoc.in b/doc/sudo_plugin.mdoc.in
index f5442088d..c942db8a8 100644
--- a/doc/sudo_plugin.mdoc.in
+++ b/doc/sudo_plugin.mdoc.in
@@ -3960,9 +3960,6 @@ the trailing NUL character).
 In practical terms, this is the longest password
 .Nm sudo
 will support.
-It is also useful as a maximum value for the
-.Fn memset_s
-function when clearing passwords filled in by the conversation function.
 .Pp
 The
 .Fn printf Ns -style
diff --git a/include/sudo_compat.h b/include/sudo_compat.h
index 879a0f3ff..03e256828 100644
--- a/include/sudo_compat.h
+++ b/include/sudo_compat.h
@@ -30,12 +30,6 @@
     !defined(HAVE_VSYSLOG) || defined(PREFER_PORTABLE_SNPRINTF)
 # include <stdarg.h>
 #endif
-#if !defined(HAVE_MEMSET_S) && !defined(rsize_t)
-# include <stddef.h>	/* for rsize_t */
-# ifdef HAVE_STRING_H
-#  include <string.h>	/* for rsize_t on AIX */
-# endif /* HAVE_STRING_H */
-#endif /* HAVE_MEMSET_S && rsize_t */
 
 /*
  * Macros and functions that may be missing on some operating systems.
@@ -442,6 +436,11 @@ __dso_public void sudo_closefrom(int);
 # undef closefrom
 # define closefrom(_a) sudo_closefrom((_a))
 #endif /* HAVE_CLOSEFROM */
+#ifndef HAVE_EXPLICIT_BZERO
+__dso_public void sudo_explicit_bzero(void *s, size_t n);
+# undef explicit_bzero
+# define explicit_bzero(_a, _b) sudo_explicit_bzero((_a), (_b))
+#endif /* HAVE_EXPLICIT_BZERO */
 #ifdef PREFER_PORTABLE_GETCWD
 __dso_public char *sudo_getcwd(char *, size_t size);
 # undef getcwd
@@ -536,11 +535,6 @@ __dso_public void *sudo_memrchr(const void *s, int c, size_t n);
 # undef memrchr
 # define memrchr(_a, _b, _c) sudo_memrchr((_a), (_b), (_c))
 #endif /* HAVE_MEMRCHR */
-#ifndef HAVE_MEMSET_S
-__dso_public errno_t sudo_memset_s(void *v, rsize_t smax, int c, rsize_t n);
-# undef memset_s
-# define memset_s(_a, _b, _c, _d) sudo_memset_s((_a), (_b), (_c), (_d))
-#endif /* HAVE_MEMSET_S */
 #if !defined(HAVE_MKDTEMP) || !defined(HAVE_MKSTEMPS)
 __dso_public char *sudo_mkdtemp(char *path);
 # undef mkdtemp
diff --git a/include/sudo_plugin.h b/include/sudo_plugin.h
index 439ef09e8..61f0f3dd9 100644
--- a/include/sudo_plugin.h
+++ b/include/sudo_plugin.h
@@ -57,9 +57,7 @@ struct sudo_conv_message {
  * conversing with the user.  In practical terms, this is the longest
  * password sudo will support.  This means that a buffer of size
  * SUDO_CONV_REPL_MAX+1 is guaranteed to be able to hold any reply
- * from the conversation function.  It is also useful as a max value
- * for memset_s() when clearing passwords returned by the conversation
- * function.
+ * from the conversation function.
  */
 #define SUDO_CONV_REPL_MAX	1023
 
diff --git a/lib/util/Makefile.in b/lib/util/Makefile.in
index f1e9a6223..342489f0f 100644
--- a/lib/util/Makefile.in
+++ b/lib/util/Makefile.in
@@ -559,6 +559,14 @@ event_select.i: $(srcdir)/event_select.c $(incdir)/compat/stdbool.h \
 	$(CC) -E -o $@ $(CPPFLAGS) $<
 event_select.plog: event_select.i
 	rm -f $@; pvs-studio --cfg $(PVS_CFG) --sourcetree-root $(top_srcdir) --skip-cl-exe yes --source-file $(srcdir)/event_select.c --i-file $< --output-file $@
+explicit_bzero.lo: $(srcdir)/explicit_bzero.c $(incdir)/sudo_compat.h \
+                   $(top_builddir)/config.h
+	$(LIBTOOL) $(LTFLAGS) --mode=compile $(CC) -c -o $@ $(CPPFLAGS) $(CFLAGS) $(ASAN_CFLAGS) $(PIE_CFLAGS) $(SSP_CFLAGS) $(srcdir)/explicit_bzero.c
+explicit_bzero.i: $(srcdir)/explicit_bzero.c $(incdir)/sudo_compat.h \
+                   $(top_builddir)/config.h
+	$(CC) -E -o $@ $(CPPFLAGS) $<
+explicit_bzero.plog: explicit_bzero.i
+	rm -f $@; pvs-studio --cfg $(PVS_CFG) --sourcetree-root $(top_srcdir) --skip-cl-exe yes --source-file $(srcdir)/explicit_bzero.c --i-file $< --output-file $@
 fatal.lo: $(srcdir)/fatal.c $(incdir)/compat/getaddrinfo.h \
           $(incdir)/compat/stdbool.h $(incdir)/sudo_compat.h \
           $(incdir)/sudo_fatal.h $(incdir)/sudo_gettext.h \
@@ -847,14 +855,6 @@ memrchr.i: $(srcdir)/memrchr.c $(incdir)/sudo_compat.h $(top_builddir)/config.h
 	$(CC) -E -o $@ $(CPPFLAGS) $<
 memrchr.plog: memrchr.i
 	rm -f $@; pvs-studio --cfg $(PVS_CFG) --sourcetree-root $(top_srcdir) --skip-cl-exe yes --source-file $(srcdir)/memrchr.c --i-file $< --output-file $@
-memset_s.lo: $(srcdir)/memset_s.c $(incdir)/sudo_compat.h \
-             $(top_builddir)/config.h
-	$(LIBTOOL) $(LTFLAGS) --mode=compile $(CC) -c -o $@ $(CPPFLAGS) $(CFLAGS) $(ASAN_CFLAGS) $(PIE_CFLAGS) $(SSP_CFLAGS) $(srcdir)/memset_s.c
-memset_s.i: $(srcdir)/memset_s.c $(incdir)/sudo_compat.h \
-             $(top_builddir)/config.h
-	$(CC) -E -o $@ $(CPPFLAGS) $<
-memset_s.plog: memset_s.i
-	rm -f $@; pvs-studio --cfg $(PVS_CFG) --sourcetree-root $(top_srcdir) --skip-cl-exe yes --source-file $(srcdir)/memset_s.c --i-file $< --output-file $@
 mkdir_parents.lo: $(srcdir)/mkdir_parents.c $(incdir)/compat/stdbool.h \
                   $(incdir)/sudo_compat.h $(incdir)/sudo_debug.h \
                   $(incdir)/sudo_fatal.h $(incdir)/sudo_gettext.h \
diff --git a/lib/util/arc4random.c b/lib/util/arc4random.c
index 4e5994951..77e3ec205 100644
--- a/lib/util/arc4random.c
+++ b/lib/util/arc4random.c
@@ -103,7 +103,7 @@ _rs_stir(void)
 		_rs_init(rnd, sizeof(rnd));
 	} else
 		_rs_rekey(rnd, sizeof(rnd));
-	memset_s(rnd, sizeof(rnd), 0, sizeof(rnd)); /* discard source seed */
+	explicit_bzero(rnd, sizeof(rnd)); /* discard source seed */
 
 	/* invalidate rs_buf */
 	rs_have = 0;
diff --git a/lib/util/explicit_bzero.c b/lib/util/explicit_bzero.c
new file mode 100644
index 000000000..a7defbd0f
--- /dev/null
+++ b/lib/util/explicit_bzero.c
@@ -0,0 +1,77 @@
+/*
+ * SPDX-License-Identifier: ISC
+ *
+ * Copyright (c) 2020 Todd C. Miller <Todd.Miller@sudo.ws>
+ *
+ * Permission to use, copy, modify, and distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
+/*
+ * This is an open source non-commercial project. Dear PVS-Studio, please check it.
+ * PVS-Studio Static Code Analyzer for C, C++ and C#: http://www.viva64.com
+ */
+
+#include <config.h>
+
+#define __STDC_WANT_LIB_EXT1__ 1	/* for memset_s() */
+
+#include <string.h>
+#ifdef HAVE_STRINGS_H
+# include <strings.h>
+#endif /* HAVE_STRINGS_H */
+
+#include "sudo_compat.h"
+
+#ifndef HAVE_EXPLICIT_BZERO
+
+# if defined(HAVE_EXPLICIT_MEMSET)
+void
+sudo_explicit_bzero(void *s, size_t n)
+{
+    explicit_memset(s, 0, n);
+}
+# elif defined(HAVE_MEMSET_EXPLICIT)
+void
+sudo_explicit_bzero(void *s, size_t n)
+{
+    memset_explicit(s, 0, n);
+}
+# elif defined(HAVE_MEMSET_S)
+void
+sudo_explicit_bzero(void *s, size_t n)
+{
+    (void)memset_s(s, n, 0, n);
+}
+# elif defined(HAVE_BZERO)
+/* Jumping through a volatile function pointer should not be optimized away. */
+void (* volatile sudo_explicit_bzero_impl)(void *, size_t) =
+    (void (*)(void *, size_t))bzero;
+
+void
+sudo_explicit_bzero(void *s, size_t n)
+{
+    sudo_explicit_bzero_impl(s, n);
+}
+# else
+void
+sudo_explicit_bzero(void *v, size_t n)
+{
+    volatile unsigned char *s = v;
+
+    /* Updating through a volatile pointer should not be optimized away. */
+    while (n--)
+	*s++ = '\0';
+}
+# endif /* HAVE_BZERO */
+
+#endif /* HAVE_EXPLICIT_BZERO */
diff --git a/lib/util/getentropy.c b/lib/util/getentropy.c
index 73d7b634a..694eb52b5 100644
--- a/lib/util/getentropy.c
+++ b/lib/util/getentropy.c
@@ -614,7 +614,7 @@ getentropy_fallback(void *buf, size_t len)
 done:
 	sudo_digest_free(ctx);
 	if (results != NULL) {
-		memset_s(results, sizeof(results), 0, sizeof(results));
+		explicit_bzero(results, sizeof(results));
 		free(results);
 	}
 	return (ret);
diff --git a/lib/util/memset_s.c b/lib/util/memset_s.c
deleted file mode 100644
index f6a04fa69..000000000
--- a/lib/util/memset_s.c
+++ /dev/null
@@ -1,78 +0,0 @@
-/*
- * SPDX-License-Identifier: ISC
- *
- * Copyright (c) 2013-2014 Todd C. Miller <Todd.Miller@sudo.ws>
- *
- * Permission to use, copy, modify, and distribute this software for any
- * purpose with or without fee is hereby granted, provided that the above
- * copyright notice and this permission notice appear in all copies.
- *
- * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
- * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
- * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
- * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
- * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
- * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
- * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
- */
-
-/*
- * This is an open source non-commercial project. Dear PVS-Studio, please check it.
- * PVS-Studio Static Code Analyzer for C, C++ and C#: http://www.viva64.com
- */
-
-#include <config.h>
-
-#include <stddef.h>
-#include <errno.h>
-#include <limits.h>
-#if defined(HAVE_STDINT_H)
-# include <stdint.h>
-#elif defined(HAVE_INTTYPES_H)
-# include <inttypes.h>
-#endif
-
-#include "sudo_compat.h"
-
-#ifndef RSIZE_MAX
-# if defined(SIZE_MAX)
-#  define RSIZE_MAX (SIZE_MAX >> 1)
-# elif defined(__LP64__)
-#  define RSIZE_MAX 0x7fffffffffffffffUL
-# else
-#  define RSIZE_MAX 0x7fffffffU
-# endif
-#endif
-
-/*
- * Simple implementation of C11 memset_s() function.
- * We use a volatile pointer when updating the byte string.
- * Most compilers will avoid optimizing away access to a
- * volatile pointer, even if the pointer appears to be unused
- * after the call.
- *
- * Note that C11 does not specify the return value on error, only
- * that it be non-zero.  We use EINVAL for all errors.
- */
-errno_t
-sudo_memset_s(void *v, rsize_t smax, int c, rsize_t n)
-{
-    errno_t ret = 0;
-    volatile unsigned char *s = v;
-
-    /* Fatal runtime-constraint violations. */
-    if (s == NULL || smax > RSIZE_MAX) {
-	ret = errno = EINVAL;
-	goto done;
-    }
-    /* Non-fatal runtime-constraint violation, n must not exceed smax. */
-    if (n > smax) {
-	n = smax;
-	ret = errno = EINVAL;
-    }
-    /* Updating through a volatile pointer should not be optimized away. */
-    while (n--)
-	*s++ = (unsigned char)c;
-done:
-    return ret;
-}
diff --git a/lib/util/sha2.c b/lib/util/sha2.c
index b8b51e6ca..b7a28cca8 100644
--- a/lib/util/sha2.c
+++ b/lib/util/sha2.c
@@ -237,8 +237,8 @@ SHA256Transform(uint32_t state[8], const uint8_t data[SHA256_BLOCK_LENGTH])
 	state[6] += g(0);
 	state[7] += h(0);
 	/* Cleanup */
-	memset_s(T, sizeof(T), 0, sizeof(T));
-	memset_s(W, sizeof(W), 0, sizeof(W));
+	explicit_bzero(T, sizeof(T));
+	explicit_bzero(W, sizeof(W));
 }
 
 #undef S0
@@ -454,8 +454,8 @@ SHA512Transform(uint64_t state[8], const uint8_t data[SHA512_BLOCK_LENGTH])
 	state[6] += g(0);
 	state[7] += h(0);
 	/* Cleanup. */
-	memset_s(T, sizeof(T), 0, sizeof(T));
-	memset_s(W, sizeof(W), 0, sizeof(W));
+	explicit_bzero(T, sizeof(T));
+	explicit_bzero(W, sizeof(W));
 }
 
 void
diff --git a/plugins/sudoers/auth/aix_auth.c b/plugins/sudoers/auth/aix_auth.c
index f9e353940..598350363 100644
--- a/plugins/sudoers/auth/aix_auth.c
+++ b/plugins/sudoers/auth/aix_auth.c
@@ -243,7 +243,7 @@ sudo_aix_verify(struct passwd *pw, char *prompt, sudo_auth *auth, struct sudo_co
 	free(message);
 	message = NULL;
 	result = authenticate(pw->pw_name, pass, &reenter, &message);
-	memset_s(pass, SUDO_CONV_REPL_MAX, 0, strlen(pass));
+	explicit_bzero(pass, strlen(pass));
 	free(pass);
 	prompt = message;
     } while (reenter);
diff --git a/plugins/sudoers/auth/bsdauth.c b/plugins/sudoers/auth/bsdauth.c
index f90e94e38..3ed6c458a 100644
--- a/plugins/sudoers/auth/bsdauth.c
+++ b/plugins/sudoers/auth/bsdauth.c
@@ -151,7 +151,7 @@ bsdauth_verify(struct passwd *pw, char *prompt, sudo_auth *auth, struct sudo_con
 
     if (pass) {
 	authok = auth_userresponse(as, pass, 1);
-	memset_s(pass, SUDO_CONV_REPL_MAX, 0, strlen(pass));
+	explicit_bzero(pass, strlen(pass));
 	free(pass);
     }
 
diff --git a/plugins/sudoers/auth/fwtk.c b/plugins/sudoers/auth/fwtk.c
index c315a352e..4c99a84a6 100644
--- a/plugins/sudoers/auth/fwtk.c
+++ b/plugins/sudoers/auth/fwtk.c
@@ -133,8 +133,8 @@ restart:
 	sudo_warnx("%s", resp);
     error = AUTH_FAILURE;
 done:
-    memset_s(buf, sizeof(buf), 0, sizeof(buf));
-    memset_s(pass, SUDO_PASS_MAX, 0, strlen(pass));
+    explicit_bzero(buf, sizeof(buf));
+    explicit_bzero(pass, strlen(pass));
     free(pass);
     debug_return_int(error);
 }
diff --git a/plugins/sudoers/auth/pam.c b/plugins/sudoers/auth/pam.c
index 6b4e24970..a725f1f62 100644
--- a/plugins/sudoers/auth/pam.c
+++ b/plugins/sudoers/auth/pam.c
@@ -702,7 +702,7 @@ converse(int num_msg, PAM_CONST struct pam_message **msg,
 		    sudo_debug_printf(SUDO_DEBUG_ERROR|SUDO_DEBUG_LINENO,
 			"password longer than %d", PAM_MAX_RESP_SIZE);
 		    ret = PAM_CONV_ERR;
-		    memset_s(pass, SUDO_CONV_REPL_MAX, 0, strlen(pass));
+		    explicit_bzero(pass, strlen(pass));
 		    goto done;
 		}
 		reply[n].resp = pass;	/* auth_getpass() malloc's a copy */
@@ -732,7 +732,7 @@ done:
 	    struct pam_response *pr = &reply[n];
 
 	    if (pr->resp != NULL) {
-		memset_s(pr->resp, SUDO_CONV_REPL_MAX, 0, strlen(pr->resp));
+		explicit_bzero(pr->resp, strlen(pr->resp));
 		free(pr->resp);
 		pr->resp = NULL;
 	    }
diff --git a/plugins/sudoers/auth/passwd.c b/plugins/sudoers/auth/passwd.c
index d83716011..305354196 100644
--- a/plugins/sudoers/auth/passwd.c
+++ b/plugins/sudoers/auth/passwd.c
@@ -101,7 +101,7 @@ sudo_passwd_cleanup(struct passwd *pw, sudo_auth *auth, bool force)
     debug_decl(sudo_passwd_cleanup, SUDOERS_DEBUG_AUTH);
 
     if (pw_epasswd != NULL) {
-	memset_s(pw_epasswd, SUDO_CONV_REPL_MAX, 0, strlen(pw_epasswd));
+	explicit_bzero(pw_epasswd, strlen(pw_epasswd));
 	free(pw_epasswd);
     }
     debug_return_int(AUTH_SUCCESS);
diff --git a/plugins/sudoers/auth/secureware.c b/plugins/sudoers/auth/secureware.c
index 1b7c98745..dd02f515e 100644
--- a/plugins/sudoers/auth/secureware.c
+++ b/plugins/sudoers/auth/secureware.c
@@ -102,7 +102,7 @@ sudo_secureware_cleanup(struct passwd *pw, sudo_auth *auth, bool force)
     debug_decl(sudo_secureware_cleanup, SUDOERS_DEBUG_AUTH);
 
     if (pw_epasswd != NULL) {
-	memset_s(pw_epasswd, SUDO_CONV_REPL_MAX, 0, strlen(pw_epasswd));
+	explicit_bzero(pw_epasswd, strlen(pw_epasswd));
 	free(pw_epasswd);
     }
     debug_return_int(AUTH_SUCCESS);
diff --git a/plugins/sudoers/auth/securid5.c b/plugins/sudoers/auth/securid5.c
index 93c712e69..e8eebdf2e 100644
--- a/plugins/sudoers/auth/securid5.c
+++ b/plugins/sudoers/auth/securid5.c
@@ -177,7 +177,7 @@ sudo_securid_verify(struct passwd *pw, char *pass, sudo_auth *auth, struct sudo_
                    ACE challenges for the next token displayed
                    (entered without the PIN) */
 		if (pass != NULL) {
-		    memset_s(pass, SUDO_PASS_MAX, 0, strlen(pass));
+		    explicit_bzero(pass, strlen(pass));
 		    free(pass);
 		}
         	pass = auth_getpass("\
@@ -218,7 +218,7 @@ then enter the new token code.\n", \
     SD_Close(*sd);
 
     if (pass != NULL) {
-	memset_s(pass, SUDO_PASS_MAX, 0, strlen(pass));
+	explicit_bzero(pass, strlen(pass));
 	free(pass);
     }
 
diff --git a/plugins/sudoers/auth/sia.c b/plugins/sudoers/auth/sia.c
index 5c7791f41..414a64b46 100644
--- a/plugins/sudoers/auth/sia.c
+++ b/plugins/sudoers/auth/sia.c
@@ -90,7 +90,7 @@ sudo_sia_verify(struct passwd *pw, char *prompt, sudo_auth *auth,
 
     /* Check password and zero out plaintext copy. */
     rc = sia_ses_authent(NULL, pass, siah);
-    memset_s(pass, SUDO_CONV_REPL_MAX, 0, strlen(pass));
+    explicit_bzero(pass, strlen(pass));
     free(pass);
 
     if (rc == SIASUCCESS)
diff --git a/plugins/sudoers/auth/sudo_auth.c b/plugins/sudoers/auth/sudo_auth.c
index 1bdacdb7c..5570c78b3 100644
--- a/plugins/sudoers/auth/sudo_auth.c
+++ b/plugins/sudoers/auth/sudo_auth.c
@@ -326,7 +326,7 @@ verify_user(struct passwd *pw, char *prompt, int validated,
 		break;
 	}
 	if (pass != NULL) {
-	    memset_s(pass, SUDO_CONV_REPL_MAX, 0, strlen(pass));
+	    explicit_bzero(pass, strlen(pass));
 	    free(pass);
 	}
 
diff --git a/scripts/mkdep.pl b/scripts/mkdep.pl
index 28e7ff05c..b42de26ee 100755
--- a/scripts/mkdep.pl
+++ b/scripts/mkdep.pl
@@ -116,7 +116,7 @@ sub mkdep {
     # XXX - fill in AUTH_OBJS from contents of the auth dir instead
     $makefile =~ s:\@AUTH_OBJS\@:afs.lo aix_auth.lo bsdauth.lo dce.lo fwtk.lo getspwuid.lo kerb5.lo pam.lo passwd.lo rfc1938.lo secureware.lo securid5.lo sia.lo:;
     $makefile =~ s:\@DIGEST\@:digest.lo digest_openssl.lo digest_gcrypt.lo:;
-    $makefile =~ s:\@LTLIBOBJS\@:arc4random.lo arc4random_uniform.lo closefrom.lo dup3.lo fchmodat.lo fstatat.lo fnmatch.lo getaddrinfo.lo getcwd.lo getentropy.lo getgrouplist.lo getdelim.lo getopt_long.lo getusershell.lo glob.lo inet_ntop_lo inet_pton.lo isblank.lo memrchr.lo memset_s.lo mksiglist.lo mksigname.lo mktemp.lo nanosleep.lo openat.lo pipe2.lo pw_dup.lo reallocarray.lo sha2.lo sig2str.lo siglist.lo signame.lo snprintf.lo str2sig.lo strlcat.lo strlcpy.lo strndup.lo strnlen.lo strsignal.lo unlinkat.lo utimens.lo vsyslog.lo:;
+    $makefile =~ s:\@LTLIBOBJS\@:arc4random.lo arc4random_uniform.lo closefrom.lo dup3.lo explicit_bzero.lo fchmodat.lo fstatat.lo fnmatch.lo getaddrinfo.lo getcwd.lo getentropy.lo getgrouplist.lo getdelim.lo getopt_long.lo getusershell.lo glob.lo inet_ntop_lo inet_pton.lo isblank.lo memrchr.lo mksiglist.lo mksigname.lo mktemp.lo nanosleep.lo openat.lo pipe2.lo pw_dup.lo reallocarray.lo sha2.lo sig2str.lo siglist.lo signame.lo snprintf.lo str2sig.lo strlcat.lo strlcpy.lo strndup.lo strnlen.lo strsignal.lo unlinkat.lo utimens.lo vsyslog.lo:;
 
     # Parse OBJS lines
     my %objs;
diff --git a/src/conversation.c b/src/conversation.c
index 55c2319c6..7a9f01ff2 100644
--- a/src/conversation.c
+++ b/src/conversation.c
@@ -80,7 +80,7 @@ sudo_conversation(int num_msgs, const struct sudo_conv_message msgs[],
 		    sudo_fatalx_nodebug(U_("%s: %s"), "sudo_conversation",
 			U_("unable to allocate memory"));
 		}
-		memset_s(pass, SUDO_CONV_REPL_MAX, 0, strlen(pass));
+		explicit_bzero(pass, strlen(pass));
 		break;
 	    case SUDO_CONV_ERROR_MSG:
 		fp = stderr;
@@ -135,7 +135,7 @@ err:
 	    struct sudo_conv_reply *repl = &replies[n];
 	    if (repl->reply == NULL)
 		continue;
-	    memset_s(repl->reply, SUDO_CONV_REPL_MAX, 0, strlen(repl->reply));
+	    explicit_bzero(repl->reply, strlen(repl->reply));
 	    free(repl->reply);
 	    repl->reply = NULL;
 	} while (n--);