diff --git a/src/env.cpp b/src/env.cpp
index bc36d4921..e58cbd79e 100644
--- a/src/env.cpp
+++ b/src/env.cpp
@@ -1283,8 +1283,9 @@ env_stack_t &env_stack_t::globals() {
     return s_globals;
 }
 
-env_stack_t &env_stack_t::principal() {
-    static env_stack_t s_principal(env_stack_impl_t::create());
+const std::shared_ptr<env_stack_t> &env_stack_t::principal_ref() {
+    static const std::shared_ptr<env_stack_t> s_principal{
+        new env_stack_t(env_stack_impl_t::create())};
     return s_principal;
 }
 
diff --git a/src/env.h b/src/env.h
index e51cee02b..6577badc5 100644
--- a/src/env.h
+++ b/src/env.h
@@ -291,7 +291,8 @@ class env_stack_t final : public environment_t {
     void mark_changed_exported();
 
     // Compatibility hack; access the "environment stack" from back when there was just one.
-    static env_stack_t &principal();
+    static const std::shared_ptr<env_stack_t> &principal_ref();
+    static env_stack_t &principal() { return *principal_ref(); }
 
     // Access a variable stack that only represents globals.
     // Do not push or pop from this.
diff --git a/src/parser.cpp b/src/parser.cpp
index 5b65f64b4..b44b5bac1 100644
--- a/src/parser.cpp
+++ b/src/parser.cpp
@@ -100,7 +100,11 @@ wcstring parser_t::user_presentable_path(const wcstring &path) const {
     return replace_home_directory_with_tilde(path, vars());
 }
 
-parser_t::parser_t() : variables(env_stack_t::principal()) {}
+parser_t::parser_t(std::shared_ptr<env_stack_t> vars) : variables(std::move(vars)) {
+    assert(variables.get() && "Null variables in parser initializer");
+}
+
+parser_t::parser_t() : parser_t(env_stack_t::principal_ref()) {}
 
 // Out of line destructor to enable forward declaration of parse_execution_context_t
 parser_t::~parser_t() = default;
diff --git a/src/parser.h b/src/parser.h
index d4ed98631..ae27c9467 100644
--- a/src/parser.h
+++ b/src/parser.h
@@ -174,7 +174,7 @@ class parser_t : public std::enable_shared_from_this<parser_t> {
     /// The 'depth' of the fish call stack.
     int eval_level = -1;
     /// Set of variables for the parser.
-    env_stack_t &variables;
+    const std::shared_ptr<env_stack_t> variables;
     /// Miscellaneous library data.
     library_data_t library_data{};
 
@@ -204,6 +204,7 @@ class parser_t : public std::enable_shared_from_this<parser_t> {
 
     /// Create a parser.
     parser_t();
+    parser_t(std::shared_ptr<env_stack_t> vars);
 
     /// The main parser.
     static std::shared_ptr<parser_t> principal;
@@ -271,8 +272,8 @@ class parser_t : public std::enable_shared_from_this<parser_t> {
     const job_list_t &jobs() const { return job_list; }
 
     /// Get the variables.
-    env_stack_t &vars() { return variables; }
-    const env_stack_t &vars() const { return variables; }
+    env_stack_t &vars() { return *variables; }
+    const env_stack_t &vars() const { return *variables; }
 
     /// Get the library data.
     library_data_t &libdata() { return library_data; }