diff --git a/src/env.cpp b/src/env.cpp
index a3aaf68d2..c05c13ecc 100644
--- a/src/env.cpp
+++ b/src/env.cpp
@@ -81,7 +81,6 @@ size_t read_byte_limit = READ_BYTE_LIMIT;
 static const wchar_t PATH_ARRAY_SEP = L':';
 static const wchar_t NONPATH_ARRAY_SEP = L' ';
 
-bool g_use_posix_spawn = false;  // will usually be set to true
 bool curses_initialized = false;
 
 /// Does the terminal have the "eat_newline_glitch".
@@ -779,11 +778,6 @@ void env_init(const struct config_paths_t *paths /* or NULL */) {
     vars.set_termsize();    // initialize the terminal size variables
     vars.set_read_limit();  // initialize the read_byte_limit
 
-    // Set g_use_posix_spawn. Default to true.
-    auto use_posix_spawn = vars.get(L"fish_use_posix_spawn");
-    g_use_posix_spawn =
-        use_posix_spawn.missing_or_empty() ? true : bool_from_string(use_posix_spawn->as_string());
-
     // Set fish_bind_mode to "default".
     vars.set_one(FISH_BIND_MODE_VAR, ENV_GLOBAL, DEFAULT_BIND_MODE);
 
diff --git a/src/env_dispatch.cpp b/src/env_dispatch.cpp
index ddadc8427..ed84ddc77 100644
--- a/src/env_dispatch.cpp
+++ b/src/env_dispatch.cpp
@@ -300,6 +300,13 @@ static void handle_curses_change(const environment_t &vars) {
     init_curses(vars);
 }
 
+static void handle_fish_use_posix_spawn_change(const environment_t &vars) {
+    // note this defaults to true
+    auto use_posix_spawn = vars.get(L"fish_use_posix_spawn");
+    g_use_posix_spawn =
+        use_posix_spawn.missing_or_empty() ? true : bool_from_string(use_posix_spawn->as_string());
+}
+
 /// Populate the dispatch table used by `env_dispatch_var_change()` to efficiently call the
 /// appropriate function to handle a change to a variable.
 /// Note this returns a new-allocated value that we expect to leak.
@@ -327,6 +334,7 @@ static std::unique_ptr<const var_dispatch_table_t> create_dispatch_table() {
     var_dispatch_table->add(L"fish_read_limit", handle_read_limit_change);
     var_dispatch_table->add(L"fish_history", handle_fish_history_change);
     var_dispatch_table->add(L"TZ", handle_tz_change);
+    var_dispatch_table->add(L"fish_use_posix_spawn", handle_fish_use_posix_spawn_change);
     return var_dispatch_table;
 }
 
@@ -336,3 +344,6 @@ static void run_inits(const environment_t &vars) {
     handle_curses_change(vars);
     update_wait_on_escape_ms(vars);
 }
+
+// Miscellaneous variables.
+bool g_use_posix_spawn = false;