diff --git a/gio/gapplicationcommandline.c b/gio/gapplicationcommandline.c
index 741aa97f1..d7be108bf 100644
--- a/gio/gapplicationcommandline.c
+++ b/gio/gapplicationcommandline.c
@@ -106,7 +106,7 @@
  * The complete example can be found here: 
  * [gapplication-example-cmdline.c](https://gitlab.gnome.org/GNOME/glib/-/blob/HEAD/gio/tests/gapplication-example-cmdline.c)
  *
- * In more complicated cases, the handling of the comandline can be
+ * In more complicated cases, the handling of the commandline can be
  * split between the launcher and the primary instance.
  * |[<!-- language="C" -->
  * static gboolean
@@ -119,6 +119,12 @@
  *
  *   argv = *arguments;
  *
+ *   if (argv[0] == NULL)
+ *     {
+ *       *exit_status = 0;
+ *       return FALSE;
+ *     }
+ *
  *   i = 1;
  *   while (argv[i])
  *     {
diff --git a/gio/gdbus-tool.c b/gio/gdbus-tool.c
index 42991886a..476056b9f 100644
--- a/gio/gdbus-tool.c
+++ b/gio/gdbus-tool.c
@@ -107,7 +107,7 @@ usage (gint *argc, gchar **argv[], gboolean use_stdout)
   g_option_context_set_help_enabled (o, FALSE);
   /* Ignore parsing result */
   g_option_context_parse (o, argc, argv, NULL);
-  program_name = g_path_get_basename ((*argv)[0]);
+  program_name = (*argc > 0) ? g_path_get_basename ((*argv)[0]) : g_strdup ("gdbus-tool");
   s = g_strdup_printf (_("Commands:\n"
                          "  help         Shows this information\n"
                          "  introspect   Introspect a remote object\n"
@@ -141,6 +141,7 @@ modify_argv0_for_command (gint *argc, gchar **argv[], const gchar *command)
    *  2. save old argv[0] and restore later
    */
 
+  g_assert (*argc > 1);
   g_assert (g_strcmp0 ((*argv)[1], command) == 0);
   remove_arg (1, argc, argv);
 
diff --git a/gio/gdesktopappinfo.c b/gio/gdesktopappinfo.c
index 058ddca2a..0d0b2c6cc 100644
--- a/gio/gdesktopappinfo.c
+++ b/gio/gdesktopappinfo.c
@@ -1880,6 +1880,10 @@ g_desktop_app_info_load_from_keyfile (GDesktopAppInfo *info,
       else
         {
           char *t;
+
+          /* Since @exec is not an empty string, there must be at least one
+           * argument, so dereferencing argv[0] should return non-NULL. */
+          g_assert (argc > 0);
           t = g_find_program_in_path (argv[0]);
           g_strfreev (argv);
 
diff --git a/gio/gio-querymodules.c b/gio/gio-querymodules.c
index cbeb9758e..aff194b73 100644
--- a/gio/gio-querymodules.c
+++ b/gio/gio-querymodules.c
@@ -161,7 +161,7 @@ main (gint   argc,
 {
   int i;
 
-  if (argc == 1)
+  if (argc <= 1)
     {
       g_print ("Usage: gio-querymodules <directory1> [<directory2> ...]\n");
       g_print ("Will update giomodule.cache in the listed directories\n");
diff --git a/glib/deprecated/gcompletion.c b/glib/deprecated/gcompletion.c
index d09c1f1fa..5f0979bb0 100644
--- a/glib/deprecated/gcompletion.c
+++ b/glib/deprecated/gcompletion.c
@@ -463,7 +463,8 @@ main (int   argc,
   
   if (argc < 3)
     {
-      g_warning ("Usage: %s filename prefix1 [prefix2 ...]", argv[0]);
+      g_warning ("Usage: %s filename prefix1 [prefix2 ...]",
+                 (argc > 0) ? argv[0] : "gcompletion");
       return 1;
     }
   
diff --git a/glib/gshell.c b/glib/gshell.c
index 33c53497a..ed893905e 100644
--- a/glib/gshell.c
+++ b/glib/gshell.c
@@ -646,6 +646,11 @@ tokenize_command_line (const gchar *command_line,
  *
  * Possible errors are those from the %G_SHELL_ERROR domain.
  *
+ * In particular, if @command_line is an empty string (or a string containing
+ * only whitespace), %G_SHELL_ERROR_EMPTY_STRING will be returned. It’s
+ * guaranteed that @argvp will be a non-empty array if this function returns
+ * successfully.
+ *
  * Free the returned vector with g_strfreev().
  * 
  * Returns: %TRUE on success, %FALSE if error set
@@ -702,7 +707,10 @@ g_shell_parse_argv (const gchar *command_line,
     }
   
   g_slist_free_full (tokens, g_free);
-  
+
+  g_assert (argc > 0);
+  g_assert (argv != NULL && argv[0] != NULL);
+
   if (argcp)
     *argcp = argc;
 
diff --git a/glib/gspawn-win32.c b/glib/gspawn-win32.c
index d3864d54d..30812dba6 100644
--- a/glib/gspawn-win32.c
+++ b/glib/gspawn-win32.c
@@ -236,7 +236,7 @@ g_spawn_async (const gchar          *working_directory,
                GPid                 *child_pid,
                GError              **error)
 {
-  g_return_val_if_fail (argv != NULL, FALSE);
+  g_return_val_if_fail (argv != NULL && argv[0] != NULL, FALSE);
   
   return g_spawn_async_with_pipes (working_directory,
                                    argv, envp,
@@ -460,6 +460,8 @@ do_spawn_directly (gint                 *exit_status,
   gint conv_error_index;
   wchar_t *wargv0, **wargv, **wenvp;
 
+  g_assert (argv != NULL && argv[0] != NULL);
+
   new_argv = (flags & G_SPAWN_FILE_AND_ARGV_ZERO) ? protected_argv + 1 : protected_argv;
       
   wargv0 = g_utf8_to_utf16 (argv[0], -1, NULL, NULL, &conv_error);
@@ -601,6 +603,7 @@ fork_exec (gint                  *exit_status,
   int stdout_pipe[2] = { -1, -1 };
   int stderr_pipe[2] = { -1, -1 };
 
+  g_assert (argv != NULL && argv[0] != NULL);
   g_assert (stdin_pipe_out == NULL || stdin_fd < 0);
   g_assert (stdout_pipe_out == NULL || stdout_fd < 0);
   g_assert (stderr_pipe_out == NULL || stderr_fd < 0);
@@ -989,7 +992,7 @@ g_spawn_sync (const gchar          *working_directory,
   gboolean failed;
   gint status;
   
-  g_return_val_if_fail (argv != NULL, FALSE);
+  g_return_val_if_fail (argv != NULL && argv[0] != NULL, FALSE);
   g_return_val_if_fail (!(flags & G_SPAWN_DO_NOT_REAP_CHILD), FALSE);
   g_return_val_if_fail (standard_output == NULL ||
                         !(flags & G_SPAWN_STDOUT_TO_DEV_NULL), FALSE);
@@ -1221,7 +1224,7 @@ g_spawn_async_with_pipes (const gchar          *working_directory,
                           gint                 *standard_error,
                           GError              **error)
 {
-  g_return_val_if_fail (argv != NULL, FALSE);
+  g_return_val_if_fail (argv != NULL && argv[0] != NULL, FALSE);
   g_return_val_if_fail (standard_output == NULL ||
                         !(flags & G_SPAWN_STDOUT_TO_DEV_NULL), FALSE);
   g_return_val_if_fail (standard_error == NULL ||
@@ -1263,7 +1266,7 @@ g_spawn_async_with_fds (const gchar          *working_directory,
                         gint                  stderr_fd,
                         GError              **error)
 {
-  g_return_val_if_fail (argv != NULL, FALSE);
+  g_return_val_if_fail (argv != NULL && argv[0] != NULL, FALSE);
   g_return_val_if_fail (stdin_fd == -1 ||
                         !(flags & G_SPAWN_STDOUT_TO_DEV_NULL), FALSE);
   g_return_val_if_fail (stderr_fd == -1 ||
@@ -1312,7 +1315,7 @@ g_spawn_async_with_pipes_and_fds (const gchar           *working_directory,
                                   gint                  *stderr_pipe_out,
                                   GError               **error)
 {
-  g_return_val_if_fail (argv != NULL, FALSE);
+  g_return_val_if_fail (argv != NULL && argv[0] != NULL, FALSE);
   g_return_val_if_fail (stdout_pipe_out == NULL ||
                         !(flags & G_SPAWN_STDOUT_TO_DEV_NULL), FALSE);
   g_return_val_if_fail (stderr_pipe_out == NULL ||
@@ -1359,6 +1362,7 @@ g_spawn_command_line_sync (const gchar  *command_line,
 
   g_return_val_if_fail (command_line != NULL, FALSE);
   
+  /* This will return a runtime error if @command_line is the empty string. */
   if (!g_shell_parse_argv (command_line,
                            NULL, &argv,
                            error))
@@ -1388,6 +1392,7 @@ g_spawn_command_line_async (const gchar *command_line,
 
   g_return_val_if_fail (command_line != NULL, FALSE);
 
+  /* This will return a runtime error if @command_line is the empty string. */
   if (!g_shell_parse_argv (command_line,
                            NULL, &argv,
                            error))
diff --git a/glib/gspawn.c b/glib/gspawn.c
index 1128221cc..cce03f81d 100644
--- a/glib/gspawn.c
+++ b/glib/gspawn.c
@@ -319,7 +319,7 @@ read_data (GString *str,
  * @working_directory: (type filename) (nullable): child's current working
  *     directory, or %NULL to inherit parent's
  * @argv: (array zero-terminated=1) (element-type filename):
- *     child's argument vector
+ *     child's argument vector, which must be non-empty and %NULL-terminated
  * @envp: (array zero-terminated=1) (element-type filename) (nullable):
  *     child's environment, or %NULL to inherit parent's
  * @flags: flags from #GSpawnFlags
@@ -378,6 +378,7 @@ g_spawn_sync (const gchar          *working_directory,
   gint status;
   
   g_return_val_if_fail (argv != NULL, FALSE);
+  g_return_val_if_fail (argv[0] != NULL, FALSE);
   g_return_val_if_fail (!(flags & G_SPAWN_DO_NOT_REAP_CHILD), FALSE);
   g_return_val_if_fail (standard_output == NULL ||
                         !(flags & G_SPAWN_STDOUT_TO_DEV_NULL), FALSE);
@@ -578,7 +579,7 @@ g_spawn_sync (const gchar          *working_directory,
  * @working_directory: (type filename) (nullable): child's current working
  *     directory, or %NULL to inherit parent's, in the GLib file name encoding
  * @argv: (array zero-terminated=1) (element-type filename): child's argument
- *     vector, in the GLib file name encoding
+ *     vector, in the GLib file name encoding; it must be non-empty and %NULL-terminated
  * @envp: (array zero-terminated=1) (element-type filename) (nullable):
  *     child's environment, or %NULL to inherit parent's, in the GLib file
  *     name encoding
@@ -610,6 +611,7 @@ g_spawn_async_with_pipes (const gchar          *working_directory,
                           GError              **error)
 {
   g_return_val_if_fail (argv != NULL, FALSE);
+  g_return_val_if_fail (argv[0] != NULL, FALSE);
   g_return_val_if_fail (standard_output == NULL ||
                         !(flags & G_SPAWN_STDOUT_TO_DEV_NULL), FALSE);
   g_return_val_if_fail (standard_error == NULL ||
@@ -646,7 +648,7 @@ g_spawn_async_with_pipes (const gchar          *working_directory,
  * @working_directory: (type filename) (nullable): child's current working
  *     directory, or %NULL to inherit parent's, in the GLib file name encoding
  * @argv: (array zero-terminated=1) (element-type filename): child's argument
- *     vector, in the GLib file name encoding
+ *     vector, in the GLib file name encoding; it must be non-empty and %NULL-terminated
  * @envp: (array zero-terminated=1) (element-type filename) (nullable):
  *     child's environment, or %NULL to inherit parent's, in the GLib file
  *     name encoding
@@ -880,6 +882,7 @@ g_spawn_async_with_pipes_and_fds (const gchar           *working_directory,
                                   GError               **error)
 {
   g_return_val_if_fail (argv != NULL, FALSE);
+  g_return_val_if_fail (argv[0] != NULL, FALSE);
   g_return_val_if_fail (stdout_pipe_out == NULL ||
                         !(flags & G_SPAWN_STDOUT_TO_DEV_NULL), FALSE);
   g_return_val_if_fail (stderr_pipe_out == NULL ||
@@ -922,7 +925,8 @@ g_spawn_async_with_pipes_and_fds (const gchar           *working_directory,
 /**
  * g_spawn_async_with_fds:
  * @working_directory: (type filename) (nullable): child's current working directory, or %NULL to inherit parent's, in the GLib file name encoding
- * @argv: (array zero-terminated=1): child's argument vector, in the GLib file name encoding
+ * @argv: (array zero-terminated=1): child's argument vector, in the GLib file name encoding;
+ *   it must be non-empty and %NULL-terminated
  * @envp: (array zero-terminated=1) (nullable): child's environment, or %NULL to inherit parent's, in the GLib file name encoding
  * @flags: flags from #GSpawnFlags
  * @child_setup: (scope async) (nullable): function to run in the child just before exec()
@@ -956,6 +960,7 @@ g_spawn_async_with_fds (const gchar          *working_directory,
                         GError              **error)
 {
   g_return_val_if_fail (argv != NULL, FALSE);
+  g_return_val_if_fail (argv[0] != NULL, FALSE);
   g_return_val_if_fail (stdout_fd < 0 ||
                         !(flags & G_SPAWN_STDOUT_TO_DEV_NULL), FALSE);
   g_return_val_if_fail (stderr_fd < 0 ||
@@ -1039,6 +1044,7 @@ g_spawn_command_line_sync (const gchar  *command_line,
 
   g_return_val_if_fail (command_line != NULL, FALSE);
   
+  /* This will return a runtime error if @command_line is the empty string. */
   if (!g_shell_parse_argv (command_line,
                            NULL, &argv,
                            error))
@@ -1086,6 +1092,7 @@ g_spawn_command_line_async (const gchar *command_line,
 
   g_return_val_if_fail (command_line != NULL, FALSE);
 
+  /* This will return a runtime error if @command_line is the empty string. */
   if (!g_shell_parse_argv (command_line,
                            NULL, &argv,
                            error))
@@ -1636,7 +1643,9 @@ enum
 };
 
 /* This function is called between fork() and exec() and hence must be
- * async-signal-safe (see signal-safety(7)) until it calls exec(). */
+ * async-signal-safe (see signal-safety(7)) until it calls exec().
+ *
+ * All callers must guarantee that @argv and @argv[0] are non-NULL. */
 static void
 do_exec (gint                  child_err_report_fd,
          gint                  stdin_fd,
@@ -1926,6 +1935,8 @@ do_posix_spawn (const gchar * const *argv,
   gsize i;
   int r;
 
+  g_assert (argv != NULL && argv[0] != NULL);
+
   if (*argv[0] == '\0')
     {
       /* We check the simple case first. */
@@ -2176,6 +2187,7 @@ fork_exec (gboolean              intermediate_child,
   gint n_child_close_fds = 0;
   gint *source_fds_copy = NULL;
 
+  g_assert (argv != NULL && argv[0] != NULL);
   g_assert (stdin_pipe_out == NULL || stdin_fd < 0);
   g_assert (stdout_pipe_out == NULL || stdout_fd < 0);
   g_assert (stderr_pipe_out == NULL || stderr_fd < 0);
@@ -2734,7 +2746,7 @@ g_execute (const gchar  *file,
            gchar        *search_path_buffer,
            gsize         search_path_buffer_len)
 {
-  if (*file == '\0')
+  if (file == NULL || *file == '\0')
     {
       /* We check the simple case first. */
       errno = ENOENT;
diff --git a/glib/gtester.c b/glib/gtester.c
index 94cfba641..c48ecaf94 100644
--- a/glib/gtester.c
+++ b/glib/gtester.c
@@ -668,8 +668,8 @@ parse_args (gint    *argc_p,
         }
     }
   /* collapse argv */
-  e = 1;
-  for (i = 1; i < argc; i++)
+  e = 0;
+  for (i = 0; i < argc; i++)
     if (argv[i])
       {
         argv[e++] = argv[i];
diff --git a/glib/gtestutils.c b/glib/gtestutils.c
index 27c72a416..dca4badcf 100644
--- a/glib/gtestutils.c
+++ b/glib/gtestutils.c
@@ -890,7 +890,7 @@ static gboolean    test_debug_log = FALSE;
 static gboolean    test_tap_log = TRUE;  /* default to TAP as of GLib 2.62; see #1619; the non-TAP output mode is deprecated */
 static gboolean    test_nonfatal_assertions = FALSE;
 static DestroyEntry *test_destroy_queue = NULL;
-static const char *test_argv0 = NULL;           /* points into global argv */
+static const char *test_argv0 = NULL;           /* (nullable), points into global argv */
 static char       *test_argv0_dirname = NULL;   /* owned by GLib */
 static const char *test_disted_files_dir;       /* points into test_argv0_dirname or an environment variable */
 static const char *test_built_files_dir;        /* points into test_argv0_dirname or an environment variable */
@@ -1138,7 +1138,7 @@ parse_args (gint    *argc_p,
   gchar **argv = *argv_p;
   guint i, e;
 
-  test_argv0 = argv[0];
+  test_argv0 = argv[0];  /* will be NULL iff argc == 0 */
   test_initial_cwd = g_get_current_dir ();
 
   /* parse known args */
@@ -1382,8 +1382,8 @@ parse_args (gint    *argc_p,
   test_paths = g_slist_reverse (test_paths);
 
   /* collapse argv */
-  e = 1;
-  for (i = 1; i < argc; i++)
+  e = 0;
+  for (i = 0; i < argc; i++)
     if (argv[i])
       {
         argv[e++] = argv[i];
@@ -1732,7 +1732,7 @@ void
   g_log_set_default_handler (gtest_default_log_handler, NULL);
   g_test_log (G_TEST_LOG_START_BINARY, g_get_prgname(), test_run_seedstr, 0, NULL);
 
-  test_argv0_dirname = g_path_get_dirname (test_argv0);
+  test_argv0_dirname = (test_argv0 != NULL) ? g_path_get_dirname (test_argv0) : g_strdup (".");
 
   /* Make sure we get the real dirname that the test was run from */
   if (g_str_has_suffix (test_argv0_dirname, "/.libs"))
@@ -3828,6 +3828,9 @@ g_test_trap_subprocess (const char           *test_path,
   test_trap_clear ();
   test_trap_last_subprocess = g_strdup (test_path);
 
+  if (test_argv0 == NULL)
+    g_error ("g_test_trap_subprocess() requires argv0 to be passed to g_test_init()");
+
   argv = g_ptr_array_new ();
   g_ptr_array_add (argv, (char *) test_argv0);
   g_ptr_array_add (argv, "-q");
diff --git a/glib/tests/testing-helper.c b/glib/tests/testing-helper.c
index 7b61e8337..7731538a0 100644
--- a/glib/tests/testing-helper.c
+++ b/glib/tests/testing-helper.c
@@ -102,6 +102,24 @@ main (int   argc,
   argc -= 1;
   argv[argc] = NULL;
 
+  if (g_strcmp0 (argv1, "init-null-argv0") == 0)
+    {
+      int test_argc = 0;
+      char *test_argva[1] = { NULL };
+      char **test_argv = test_argva;
+
+      /* Test that `g_test_init()` can handle being called with an empty argv
+       * and argc == 0. While this isn’t recommended, it is possible for another
+       * process to use execve() to call a gtest process this way, so we’d
+       * better handle it gracefully.
+       *
+       * This test can’t be run after `g_test_init()` has been called normally,
+       * as it isn’t allowed to be called more than once in a process. */
+      g_test_init (&test_argc, &test_argv, NULL);
+
+      return 0;
+    }
+
   g_test_init (&argc, &argv, NULL);
   g_test_set_nonfatal_assertions ();
 
diff --git a/glib/tests/testing.c b/glib/tests/testing.c
index c1fcd8c67..accd5dbfe 100644
--- a/glib/tests/testing.c
+++ b/glib/tests/testing.c
@@ -1585,6 +1585,40 @@ test_tap_summary (void)
   g_ptr_array_unref (argv);
 }
 
+static void
+test_init_no_argv0 (void)
+{
+  const char *testing_helper;
+  GPtrArray *argv;
+  GError *error = NULL;
+  int status;
+  gchar *output;
+
+  g_test_summary ("Test that g_test_init() can be called safely with argc == 0.");
+
+  testing_helper = g_test_get_filename (G_TEST_BUILT, "testing-helper" EXEEXT, NULL);
+
+  argv = g_ptr_array_new ();
+  g_ptr_array_add (argv, (char *) testing_helper);
+  g_ptr_array_add (argv, "init-null-argv0");
+  g_ptr_array_add (argv, NULL);
+
+  /* This has to be spawned manually and can’t be run with g_test_subprocess()
+   * because the test helper can’t be run after `g_test_init()` has been called
+   * in the process. */
+  g_spawn_sync (NULL, (char **) argv->pdata, NULL,
+                G_SPAWN_STDERR_TO_DEV_NULL,
+                NULL, NULL, &output, NULL, &status,
+                &error);
+  g_assert_no_error (error);
+
+  g_spawn_check_wait_status (status, &error);
+  g_assert_no_error (error);
+  g_assert_nonnull (strstr (output, "# random seed:"));
+  g_free (output);
+  g_ptr_array_unref (argv);
+}
+
 int
 main (int   argc,
       char *argv[])
@@ -1682,6 +1716,8 @@ main (int   argc,
   g_test_add_func ("/tap", test_tap);
   g_test_add_func ("/tap/summary", test_tap_summary);
 
+  g_test_add_func ("/init/no_argv0", test_init_no_argv0);
+
   ret = g_test_run ();
 
   /* We can't test for https://gitlab.gnome.org/GNOME/glib/-/issues/2563
diff --git a/glib/win_iconv.c b/glib/win_iconv.c
index cc2ce53b6..7c78e78fc 100644
--- a/glib/win_iconv.c
+++ b/glib/win_iconv.c
@@ -2034,7 +2034,8 @@ main(int argc, char **argv)
 
     if (fromcode == NULL || tocode == NULL)
     {
-        printf("usage: %s [-c] -f from-enc -t to-enc [file]\n", argv[0]);
+        printf("usage: %s [-c] -f from-enc -t to-enc [file]\n",
+               (argc > 0) ? argv[0] : "win_iconv");
         return 0;
     }
 
diff --git a/gobject/gobject-query.c b/gobject/gobject-query.c
index fd45fba82..5c3c7dc42 100644
--- a/gobject/gobject-query.c
+++ b/gobject/gobject-query.c
@@ -196,7 +196,7 @@ main (gint   argc,
     }
   
   if (!gen_froots && !gen_tree)
-    return help (argv[i-1]);
+    return help ((argc > 0) ? argv[i-1] : NULL);
   
   if (!indent_inc)
     {