diff --git a/epicardium/api/interrupt-sender.c b/epicardium/api/interrupt-sender.c
index 804b0a8bbe0d48224f4a9aee538f9f60e1c389a3..fb0c65a7c189fbdfa329e8a6a8acdfb67db97c64 100644
--- a/epicardium/api/interrupt-sender.c
+++ b/epicardium/api/interrupt-sender.c
@@ -7,7 +7,7 @@ static bool enabled[API_INT_MAX + 1];
 int api_interrupt_trigger(api_int_id_t id)
 {
 	if (id > API_INT_MAX) {
-		return EINVAL;
+		return -EINVAL;
 	}
 
 	if (enabled[id]) {
@@ -32,7 +32,7 @@ void api_interrupt_init(void)
 int epic_interrupt_enable(api_int_id_t int_id)
 {
 	if (int_id > API_INT_MAX) {
-		return EINVAL;
+		return -EINVAL;
 	}
 
 	enabled[int_id] = true;
@@ -42,7 +42,7 @@ int epic_interrupt_enable(api_int_id_t int_id)
 int epic_interrupt_disable(api_int_id_t int_id)
 {
 	if (int_id > API_INT_MAX) {
-		return EINVAL;
+		return -EINVAL;
 	}
 
 	enabled[int_id] = false;
diff --git a/pycardium/mpconfigport.h b/pycardium/mpconfigport.h
index d71bf5d4d34d8aec39eff5f027c52fa69f8df14b..2f1ba15ae305833be7f6fb7f5323a82f0dfa583a 100644
--- a/pycardium/mpconfigport.h
+++ b/pycardium/mpconfigport.h
@@ -35,6 +35,8 @@
 #define MICROPY_PY_URE_MATCH_SPAN_START_END (1)
 #define MICROPY_PY_URE_SUB                  (1)
 #define MICROPY_PY_UTIME_MP_HAL             (1)
+#define MICROPY_PY_THREAD                           (1)
+#define MICROPY_PY_THREAD_GIL                       (1)
 
 /* Modules */
 #define MODULE_UTIME_ENABLED                (1)