diff --git a/bare-arm/main.c b/bare-arm/main.c
index e6ce06398..99a7f926e 100644
--- a/bare-arm/main.c
+++ b/bare-arm/main.c
@@ -48,6 +48,7 @@ mp_obj_t mp_builtin_open(size_t n_args, const mp_obj_t *args, mp_map_t *kwargs)
 MP_DEFINE_CONST_FUN_OBJ_KW(mp_builtin_open_obj, 1, mp_builtin_open);
 
 void nlr_jump_fail(void *val) {
+    while (1);
 }
 
 void NORETURN __fatal_error(const char *msg) {
diff --git a/minimal/main.c b/minimal/main.c
index 6b77b1a42..766ad6c1b 100644
--- a/minimal/main.c
+++ b/minimal/main.c
@@ -87,6 +87,7 @@ mp_obj_t mp_builtin_open(uint n_args, const mp_obj_t *args, mp_map_t *kwargs) {
 MP_DEFINE_CONST_FUN_OBJ_KW(mp_builtin_open_obj, 1, mp_builtin_open);
 
 void nlr_jump_fail(void *val) {
+    while (1);
 }
 
 void NORETURN __fatal_error(const char *msg) {
diff --git a/py/nlr.h b/py/nlr.h
index 6c86fc26c..00c1072fe 100644
--- a/py/nlr.h
+++ b/py/nlr.h
@@ -82,7 +82,7 @@ NORETURN void nlr_jump(void *val);
 // This must be implemented by a port.  It's called by nlr_jump
 // if no nlr buf has been pushed.  It must not return, but rather
 // should bail out with a fatal error.
-void nlr_jump_fail(void *val);
+NORETURN void nlr_jump_fail(void *val);
 
 // use nlr_raise instead of nlr_jump so that debugging is easier
 #ifndef DEBUG
diff --git a/qemu-arm/main.c b/qemu-arm/main.c
index b6ff73980..aa7247b44 100644
--- a/qemu-arm/main.c
+++ b/qemu-arm/main.c
@@ -1,4 +1,5 @@
 #include <stdint.h>
+#include <stdlib.h>
 #include <stdio.h>
 #include <string.h>
 #include <malloc.h>
@@ -59,4 +60,6 @@ mp_obj_t mp_builtin_open(size_t n_args, const mp_obj_t *args, mp_map_t *kwargs)
 MP_DEFINE_CONST_FUN_OBJ_KW(mp_builtin_open_obj, 1, mp_builtin_open);
 
 void nlr_jump_fail(void *val) {
+    printf("uncaught NLR\n");
+    exit(1);
 }
diff --git a/qemu-arm/test_main.c b/qemu-arm/test_main.c
index 5c0c915c4..4d8993090 100644
--- a/qemu-arm/test_main.c
+++ b/qemu-arm/test_main.c
@@ -1,4 +1,5 @@
 #include <stdint.h>
+#include <stdlib.h>
 #include <stdio.h>
 #include <string.h>
 #include <malloc.h>
@@ -92,4 +93,6 @@ mp_obj_t mp_builtin_open(size_t n_args, const mp_obj_t *args, mp_map_t *kwargs)
 MP_DEFINE_CONST_FUN_OBJ_KW(mp_builtin_open_obj, 1, mp_builtin_open);
 
 void nlr_jump_fail(void *val) {
+    printf("uncaught NLR\n");
+    exit(1);
 }