diff --git a/MANIFEST b/MANIFEST
index c8296e523..5c441feb4 100644
--- a/MANIFEST
+++ b/MANIFEST
@@ -742,6 +742,7 @@ plugins/sudoers/regress/cvtsudoers/test8.out.ok
 plugins/sudoers/regress/cvtsudoers/test8.sh
 plugins/sudoers/regress/cvtsudoers/test9.out.ok
 plugins/sudoers/regress/cvtsudoers/test9.sh
+plugins/sudoers/regress/editor/check_editor.c
 plugins/sudoers/regress/env_match/check_env_pattern.c
 plugins/sudoers/regress/env_match/data
 plugins/sudoers/regress/exptilde/check_exptilde.c
diff --git a/plugins/sudoers/Makefile.in b/plugins/sudoers/Makefile.in
index 06ca21f2e..662567dd7 100644
--- a/plugins/sudoers/Makefile.in
+++ b/plugins/sudoers/Makefile.in
@@ -155,9 +155,10 @@ SHELL = @SHELL@
 PROGS = sudoers.la visudo sudoreplay cvtsudoers testsudoers
 
 # Regression tests
-TEST_PROGS = check_addr check_base64 check_digest check_env_pattern \
-	     check_exptilde check_fill check_gentime check_hexchar \
-	     check_iolog_plugin check_starttime check_unesc @SUDOERS_TEST_PROGS@
+TEST_PROGS = check_addr check_base64 check_digest check_editor \
+	     check_env_pattern check_exptilde check_fill check_gentime \
+	     check_hexchar check_iolog_plugin check_starttime \
+	     check_unesc @SUDOERS_TEST_PROGS@
 
 # Fuzzers
 LIB_FUZZING_ENGINE = @FUZZ_ENGINE@
@@ -224,6 +225,8 @@ CHECK_BASE64_OBJS = check_base64.o b64_decode.lo b64_encode.o sudoers_debug.lo
 
 CHECK_DIGEST_OBJS = check_digest.o filedigest.lo digestname.lo sudoers_debug.lo
 
+CHECK_EDITOR_OBJS = check_editor.o editor.lo sudoers_debug.lo
+
 CHECK_ENV_MATCH_OBJS = check_env_pattern.o env_pattern.lo sudoers_debug.lo
 
 CHECK_EXPTILDE_OBJS = check_exptilde.o exptilde.lo pwutil.lo pwutil_impl.lo redblack.lo sudoers_debug.lo
@@ -360,6 +363,9 @@ check_base64: $(CHECK_BASE64_OBJS) $(LIBUTIL)
 check_digest: $(CHECK_DIGEST_OBJS) $(LIBUTIL)
 	$(LIBTOOL) $(LTFLAGS) --mode=link $(CC) -o $@ $(CHECK_DIGEST_OBJS) $(LDFLAGS) $(ASAN_LDFLAGS) $(PIE_LDFLAGS) $(SSP_LDFLAGS) $(LIBS)
 
+check_editor: $(CHECK_EDITOR_OBJS) $(LIBUTIL)
+	$(LIBTOOL) $(LTFLAGS) --mode=link $(CC) -o $@ $(CHECK_EDITOR_OBJS) $(LDFLAGS) $(ASAN_LDFLAGS) $(PIE_LDFLAGS) $(SSP_LDFLAGS) $(LIBS)
+
 check_env_pattern: $(CHECK_ENV_MATCH_OBJS) $(LIBUTIL)
 	$(LIBTOOL) $(LTFLAGS) --mode=link $(CC) -o $@ $(CHECK_ENV_MATCH_OBJS) $(LDFLAGS) $(ASAN_LDFLAGS) $(PIE_LDFLAGS) $(SSP_LDFLAGS) $(LIBS)
 
@@ -1118,6 +1124,30 @@ check_digest.i: $(srcdir)/regress/parser/check_digest.c \
 	$(CC) -E -o $@ $(CPPFLAGS) $<
 check_digest.plog: check_digest.i
 	rm -f $@; pvs-studio --cfg $(PVS_CFG) --sourcetree-root $(top_srcdir) --skip-cl-exe yes --source-file $(srcdir)/regress/parser/check_digest.c --i-file $< --output-file $@
+check_editor.o: $(srcdir)/regress/editor/check_editor.c $(devdir)/def_data.c \
+                $(devdir)/def_data.h $(incdir)/compat/stdbool.h \
+                $(incdir)/sudo_compat.h $(incdir)/sudo_conf.h \
+                $(incdir)/sudo_debug.h $(incdir)/sudo_eventlog.h \
+                $(incdir)/sudo_fatal.h $(incdir)/sudo_gettext.h \
+                $(incdir)/sudo_plugin.h $(incdir)/sudo_queue.h \
+                $(incdir)/sudo_util.h $(srcdir)/defaults.h $(srcdir)/logging.h \
+                $(srcdir)/parse.h $(srcdir)/sudo_nss.h $(srcdir)/sudoers.h \
+                $(srcdir)/sudoers_debug.h $(top_builddir)/config.h \
+                $(top_builddir)/pathnames.h
+	$(CC) -c $(CPPFLAGS) $(CFLAGS) $(ASAN_CFLAGS) $(PIE_CFLAGS) $(SSP_CFLAGS) $(srcdir)/regress/editor/check_editor.c
+check_editor.i: $(srcdir)/regress/editor/check_editor.c $(devdir)/def_data.c \
+                $(devdir)/def_data.h $(incdir)/compat/stdbool.h \
+                $(incdir)/sudo_compat.h $(incdir)/sudo_conf.h \
+                $(incdir)/sudo_debug.h $(incdir)/sudo_eventlog.h \
+                $(incdir)/sudo_fatal.h $(incdir)/sudo_gettext.h \
+                $(incdir)/sudo_plugin.h $(incdir)/sudo_queue.h \
+                $(incdir)/sudo_util.h $(srcdir)/defaults.h $(srcdir)/logging.h \
+                $(srcdir)/parse.h $(srcdir)/sudo_nss.h $(srcdir)/sudoers.h \
+                $(srcdir)/sudoers_debug.h $(top_builddir)/config.h \
+                $(top_builddir)/pathnames.h
+	$(CC) -E -o $@ $(CPPFLAGS) $<
+check_editor.plog: check_editor.i
+	rm -f $@; pvs-studio --cfg $(PVS_CFG) --sourcetree-root $(top_srcdir) --skip-cl-exe yes --source-file $(srcdir)/regress/editor/check_editor.c --i-file $< --output-file $@
 check_env_pattern.o: $(srcdir)/regress/env_match/check_env_pattern.c \
                      $(devdir)/def_data.h $(incdir)/compat/stdbool.h \
                      $(incdir)/sudo_compat.h $(incdir)/sudo_conf.h \
diff --git a/plugins/sudoers/editor.c b/plugins/sudoers/editor.c
index a0cd63d43..70b8cdf64 100644
--- a/plugins/sudoers/editor.c
+++ b/plugins/sudoers/editor.c
@@ -41,7 +41,7 @@ static const char *
 wordsplit(const char *str, const char *endstr, const char **last)
 {
     const char *cp;
-    debug_decl(wordsplit, SUDO_DEBUG_UTIL);
+    debug_decl(wordsplit, SUDOERS_DEBUG_UTIL);
 
     /* If no str specified, use last ptr (if any). */
     if (str == NULL) {
@@ -72,7 +72,7 @@ wordsplit(const char *str, const char *endstr, const char **last)
 
     /* Scan str until we encounter white space. */
     for (cp = str; cp < endstr; cp++) {
-	if (*cp == '\\') {
+	if (cp[0] == '\\' && cp[1] != '\0') {
 	    /* quoted char, do not interpret */
 	    cp++;
 	    continue;
@@ -96,7 +96,7 @@ copy_arg(const char *src, size_t len)
 
     if ((copy = malloc(len + 1)) != NULL) {
 	for (dst = copy; src < src_end; ) {
-	    if (*src == '\\') {
+	    if (src[0] == '\\' && src[1] != '\0') {
 		src++;
 		continue;
 	    }
diff --git a/plugins/sudoers/regress/editor/check_editor.c b/plugins/sudoers/regress/editor/check_editor.c
new file mode 100644
index 000000000..7653c94eb
--- /dev/null
+++ b/plugins/sudoers/regress/editor/check_editor.c
@@ -0,0 +1,142 @@
+/*
+ * SPDX-License-Identifier: ISC
+ *
+ * Copyright (c) 2021 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.
+ */
+
+#include <config.h>
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#define SUDO_ERROR_WRAP 0
+
+#include "sudoers.h"
+#include <def_data.c>
+
+/* Note hard-coded array lengths. */
+struct test_data {
+    char *editor_var;
+    int nfiles;
+    char *files[4];
+    char *editor_path;
+    int edit_argc;
+    char *edit_argv[10];
+} test_data[] = {
+    {
+	/* Bug #942 */
+	"SUDO_EDITOR=sh -c \"vi \\$1\"",
+	1,
+	{ "/etc/motd", NULL },
+	"/usr/bin/sh",
+	5,
+	{ "sh", "-c", "vi $1", "--", "/etc/motd", NULL }
+    },
+    {
+	/* GitHub issue #99 */
+	"EDITOR=/usr/bin/vi\\",
+	1,
+	{ "/etc/hosts", "/bogus/file", NULL },
+	"/usr/bin/vi\\",
+	3,
+	{ "/usr/bin/vi\\", "--", "/etc/hosts", "/bogus/file", NULL }
+    },
+    { NULL }
+};
+
+sudo_dso_public int main(int argc, char *argv[]);
+
+/* STUB */
+int
+find_path(const char *infile, char **outfile, struct stat *sbp,
+    const char *path, const char *runchroot, int ignore_dot,
+    char * const *allowlist)
+{
+    if (infile[0] == '/') {
+	*outfile = strdup(infile);
+    } else {
+	if (asprintf(outfile, "/usr/bin/%s", infile) == -1)
+	    *outfile = NULL;
+    }
+    if (*outfile == NULL)
+	return NOT_FOUND_ERROR;
+    return FOUND;
+}
+
+int
+main(int argc, char *argv[])
+{
+    struct test_data *data;
+    int ntests = 0, errors = 0;
+
+    initprogname(argc > 0 ? argv[0] : "check_editor");
+
+    for (data = test_data; data->editor_var != NULL; data++) {
+	const char *env_editor = NULL;
+	char *cp, *editor_path, **edit_argv = NULL;
+	int i, edit_argc = 0;
+
+	/* clear existing editor environment vars */
+	putenv("VISUAL=");
+	putenv("EDITOR=");
+	putenv("SUDO_EDITOR=");
+
+	putenv(data->editor_var);
+	editor_path = find_editor(data->nfiles, data->files, &edit_argc,
+	    &edit_argv, NULL, &env_editor, false);
+	ntests++;
+	if (strcmp(editor_path, data->editor_path) != 0) {
+	    sudo_warnx("test %d: editor_path: expected \"%s\", got \"%s\"",
+		ntests, data->editor_path, editor_path);
+	    errors++;
+	}
+	ntests++;
+	cp = strchr(data->editor_var, '=') + 1;
+	if (strcmp(env_editor, cp) != 0) {
+	    sudo_warnx("test %d: env_editor: expected \"%s\", got \"%s\"",
+		ntests, cp, env_editor ? env_editor : "(NULL)");
+	    errors++;
+	}
+	ntests++;
+	if (edit_argc != data->edit_argc) {
+	    sudo_warnx("test %d: edit_argc: expected %d, got %d",
+		ntests, data->edit_argc, edit_argc);
+	    errors++;
+	} else {
+	    ntests++;
+	    for (i = 0; i < edit_argc; i++) {
+		if (strcmp(edit_argv[i], data->edit_argv[i]) != 0) {
+		    sudo_warnx("test %d: edit_argv[%d]: expected \"%s\", got \"%s\"",
+			ntests, i, data->edit_argv[i], edit_argv[i]);
+		    errors++;
+		    break;
+		}
+	    }
+	}
+
+	free(editor_path);
+	edit_argc -= data->nfiles + 1;
+	for (i = 0; i < edit_argc; i++) {
+	    free(edit_argv[i]);
+	}
+	free(edit_argv);
+    }
+
+    printf("%s: %d tests run, %d errors, %d%% success rate\n", getprogname(),
+	ntests, errors, (ntests - errors) * 100 / ntests);
+
+    exit(errors);
+}