diff --git a/epicardium/epicardium.h b/epicardium/epicardium.h
index ece91dec7378c37f1d6cbd64a5a9733fbb5eadfc..9c4a770dd2ca448d94c011b76cc3801404e9194f 100644
--- a/epicardium/epicardium.h
+++ b/epicardium/epicardium.h
@@ -465,23 +465,23 @@ API(API_LIGHT_SENSOR_STOP, int epic_light_sensor_stop());
 /** */
 API(
 	API_FILE_OPEN,
-	int32_t epic_file_open(const char* filename, const char* modeString)
+	int epic_file_open(const char* filename, const char* modeString)
 );
 
 /** */
-API(API_FILE_CLOSE, int32_t epic_file_close(int32_t fd));
+API(API_FILE_CLOSE, int epic_file_close(int fd));
 
 /** */
-API(API_FILE_READ,  int32_t epic_file_read(int32_t fd, void* buf, uint32_t nbytes));
+API(API_FILE_READ, int epic_file_read(int fd, void* buf, size_t nbytes));
 
 /** */
 API(
 	API_FILE_WRITE,
-	int32_t epic_file_write(int32_t fd, const void* buf, uint32_t nbytes)
+	int epic_file_write(int fd, const void* buf, size_t nbytes)
 );
 
 /** */
-API(API_FILE_FLUSH, int32_t epic_file_flush(int32_t fd));
+API(API_FILE_FLUSH, int epic_file_flush(int fd));
 
 /** */
 enum epic_stat_type {
@@ -510,6 +510,6 @@ typedef struct epic_stat_t {
  *
  * :return: `0` on success, negative on error
  */
-API(API_FILE_STAT, int32_t epic_file_stat(const char* path, epic_stat_t* stat));
+API(API_FILE_STAT, int epic_file_stat(const char* path, epic_stat_t* stat));
 
 #endif /* _EPICARDIUM_H */
diff --git a/epicardium/modules/fatfs.c b/epicardium/modules/fatfs.c
index 8be070c33017ecabd8a2a58286cbbe48e380ca01..649ba730374bbf2901c42373aa8f8b8575d903f8 100644
--- a/epicardium/modules/fatfs.c
+++ b/epicardium/modules/fatfs.c
@@ -203,7 +203,7 @@ int get_fat_object(int i, enum FatObjectType expected, struct FatObject **res)
 	return 0;
 }
 
-int32_t epic_file_open(const char *filename, const char *modeString)
+int epic_file_open(const char *filename, const char *modeString)
 {
 	struct FatObject *o = NULL;
 	const char *mode_s  = modeString;
@@ -255,7 +255,7 @@ int32_t epic_file_open(const char *filename, const char *modeString)
 	return i;
 }
 
-int32_t epic_file_close(int32_t fd)
+int epic_file_close(int fd)
 {
 	int res;
 	struct FatObject *o;
@@ -273,7 +273,7 @@ int32_t epic_file_close(int32_t fd)
 	return 0;
 }
 
-int32_t epic_file_read(int32_t fd, void *buf, uint32_t nbytes)
+int epic_file_read(int fd, void *buf, size_t nbytes)
 {
 	unsigned int nread = 0;
 
@@ -292,7 +292,7 @@ int32_t epic_file_read(int32_t fd, void *buf, uint32_t nbytes)
 	return nread;
 }
 
-int32_t epic_file_write(int32_t fd, const void *buf, uint32_t nbytes)
+int epic_file_write(int fd, const void *buf, size_t nbytes)
 {
 	unsigned int nwritten = 0;
 
@@ -310,7 +310,7 @@ int32_t epic_file_write(int32_t fd, const void *buf, uint32_t nbytes)
 	return nwritten;
 }
 
-int32_t epic_file_flush(int32_t fd)
+int epic_file_flush(int fd)
 {
 	int res;
 	struct FatObject *o;
@@ -326,7 +326,7 @@ int32_t epic_file_flush(int32_t fd)
 	return 0;
 }
 
-int32_t epic_file_stat(const char *filename, epic_stat_t *stat)
+int epic_file_stat(const char *filename, epic_stat_t *stat)
 {
 	int res;
 	FILINFO finfo;