diff --git a/ports/unix/mpconfigport.h b/ports/unix/mpconfigport.h
index c20aff168..2de05a0a6 100644
--- a/ports/unix/mpconfigport.h
+++ b/ports/unix/mpconfigport.h
@@ -134,12 +134,6 @@ typedef long mp_off_t;
 #define MICROPY_STACKLESS_STRICT    (0)
 #endif
 
-// If settrace is enabled then we need code saving.
-#if MICROPY_PY_SYS_SETTRACE
-#define MICROPY_PERSISTENT_CODE_SAVE (1)
-#define MICROPY_COMP_CONST (0)
-#endif
-
 // Unix-specific configuration of machine.mem*.
 #define MICROPY_MACHINE_MEM_GET_READ_ADDR   mod_machine_mem_get_addr
 #define MICROPY_MACHINE_MEM_GET_WRITE_ADDR  mod_machine_mem_get_addr
diff --git a/py/mpconfig.h b/py/mpconfig.h
index de4a89206..46c62913c 100644
--- a/py/mpconfig.h
+++ b/py/mpconfig.h
@@ -312,9 +312,11 @@
 #define MICROPY_PERSISTENT_CODE_LOAD (0)
 #endif
 
-// Whether to support saving of persistent code
+// Whether to support saving of persistent code, i.e. for mpy-cross to
+// generate .mpy files. Enabling this enables additional metadata on raw code
+// objects which is also required for sys.settrace.
 #ifndef MICROPY_PERSISTENT_CODE_SAVE
-#define MICROPY_PERSISTENT_CODE_SAVE (0)
+#define MICROPY_PERSISTENT_CODE_SAVE (MICROPY_PY_SYS_SETTRACE)
 #endif
 
 // Whether to support saving persistent code to a file via mp_raw_code_save_file
@@ -2013,14 +2015,4 @@ typedef double mp_float_t;
 #define MP_WARN_CAT(x) (NULL)
 #endif
 
-// Feature dependency check.
-#if MICROPY_PY_SYS_SETTRACE
-#if !MICROPY_PERSISTENT_CODE_SAVE
-#error "MICROPY_PY_SYS_SETTRACE requires MICROPY_PERSISTENT_CODE_SAVE to be enabled"
-#endif
-#if MICROPY_COMP_CONST
-#error "MICROPY_PY_SYS_SETTRACE requires MICROPY_COMP_CONST to be disabled"
-#endif
-#endif
-
 #endif // MICROPY_INCLUDED_PY_MPCONFIG_H
diff --git a/py/profile.c b/py/profile.c
index 89af8640a..274089d70 100644
--- a/py/profile.c
+++ b/py/profile.c
@@ -31,6 +31,12 @@
 
 #if MICROPY_PY_SYS_SETTRACE
 
+#if !MICROPY_PERSISTENT_CODE_SAVE
+// The settrace feature requires that we maintain additional metadata on the raw
+// code object which is normally only done when writing .mpy files.
+#error "MICROPY_PY_SYS_SETTRACE requires MICROPY_PERSISTENT_CODE_SAVE to be enabled"
+#endif
+
 #define prof_trace_cb MP_STATE_THREAD(prof_trace_callback)
 #define QSTR_MAP(context, idx) (context->constants.qstr_table[idx])
 
diff --git a/tests/misc/sys_settrace_features.py b/tests/misc/sys_settrace_features.py
index 84cf875a8..8ca6b382e 100644
--- a/tests/misc/sys_settrace_features.py
+++ b/tests/misc/sys_settrace_features.py
@@ -67,6 +67,11 @@ def trace_tick_handler(frame, event, arg):
     if any(name in frame_name for name in to_ignore):
         return
 
+    # Lines 4,5,7 create the `const` lambda, and line `15` is a `_X = const()` which
+    # MicroPython will not see as it's optimised out.
+    if "sys_settrace_importme" in frame.f_code.co_filename and frame.f_lineno in (4, 5, 7, 15):
+        return trace_tick_handler
+
     print("### trace_handler::main event:", event)
     __prof__.trace_tick(frame, event, arg)
 
diff --git a/tests/misc/sys_settrace_subdir/sys_settrace_importme.py b/tests/misc/sys_settrace_subdir/sys_settrace_importme.py
index de561ef21..fdfa06134 100644
--- a/tests/misc/sys_settrace_subdir/sys_settrace_importme.py
+++ b/tests/misc/sys_settrace_subdir/sys_settrace_importme.py
@@ -3,12 +3,18 @@ print("Yep, I got imported.")
 try:
     x = const(1)
 except NameError:
-    print("const not defined")
+    # Either running on CPython or MICROPY_COMP_CONST disabled.
+    const = lambda x: x
 
-const = lambda x: x
 
+# No const optimisation.
 _CNT01 = "CONST01"
+
+# Const assigned to an underscore name. Invisible to MicroPython with
+# MICROPY_COMP_CONST enabled.
 _CNT02 = const(123)
+
+# Consts assigned to regular name, executed normally.
 A123 = const(123)
 a123 = const(123)