diff --git a/preload/apps/spo2/__init__.py b/preload/apps/spo2/__init__.py
index 7caf8f9ecf100decb9f6dcd701a3424517b9d783..3fb4be272f4f078e48c29982d22b76b035346cbc 100644
--- a/preload/apps/spo2/__init__.py
+++ b/preload/apps/spo2/__init__.py
@@ -42,20 +42,21 @@ class SPO2:
                 self.disp.clear(self.COLOR_BACKGROUND)
                 self.draw_histogram(self.ir_history, color.RED)
                 self.draw_histogram(self.red_history, color.GREEN)
-                spo2, spo2_valid, hr, hr_valid = spo2_algo.maxim_rd117(self.ir_history, self.red_history)
+                spo2, spo2_valid, hr, hr_valid = spo2_algo.maxim_rd117(
+                    self.ir_history, self.red_history
+                )
 
                 print(utime.time_ms() - self.t0, spo2, spo2_valid, hr, hr_valid)
                 self.t0 = utime.time_ms()
                 if hr_valid:
-                    self.disp.print('HR: {0:3} bpm'.format(hr), posy=20)
+                    self.disp.print("HR: {0:3} bpm".format(hr), posy=20)
                 else:
-                    self.disp.print('HR: --- bpm'.format(hr), posy=20)
+                    self.disp.print("HR: --- bpm".format(hr), posy=20)
 
                 if spo2_valid:
-                    self.disp.print('SpO2: {0:3}%'.format(spo2), posy=0)
+                    self.disp.print("SpO2: {0:3}%".format(spo2), posy=0)
                 else:
-                    self.disp.print('SpO2: ---%'.format(spo2), posy=0)
-
+                    self.disp.print("SpO2: ---%".format(spo2), posy=0)
 
                 self.disp.update()
                 """
@@ -76,14 +77,15 @@ class SPO2:
         # 4x over sampling is active ATM
         self.sensor = max86150.MAX86150(callback=callback, sample_rate=self.RATE * 4)
         while True:
-            utime.sleep(.1)
+            utime.sleep(0.1)
             if buttons.read(buttons.BOTTOM_RIGHT):
                 pass
-            while buttons.read(buttons.BOTTOM_RIGHT): pass
+            while buttons.read(buttons.BOTTOM_RIGHT):
+                pass
 
     def update_history(self, datasets):
         for val in datasets:
-            #print("%d,%d" % (val.red, val.infrared))
+            # print("%d,%d" % (val.red, val.infrared))
 
             self.ir_history.append(val.infrared)
             self.red_history.append(val.red)
@@ -141,7 +143,6 @@ class SPO2:
             self.disp.line(x, prev, x + 1, value, col=col)
             prev = value
 
-
     def close(self):
         if self.self is not None:
             self.sensor.close()
diff --git a/pycardium/modules/spo2_algo.c b/pycardium/modules/spo2_algo.c
index c10ae6386b28b8b4c4ecc5fa437059b2b7a19291..04a6f2c3276dfcd4327740854ef8722762809595 100644
--- a/pycardium/modules/spo2_algo.c
+++ b/pycardium/modules/spo2_algo.c
@@ -5,17 +5,16 @@
 #include "py/obj.h"
 #include "py/runtime.h"
 
-static mp_obj_t
-mp_maxim_rd177(mp_obj_t ir, mp_obj_t red)
+static mp_obj_t mp_maxim_rd177(mp_obj_t ir, mp_obj_t red)
 {
 	uint32_t pun_ir_buffer[500];
 	uint32_t pun_red_buffer[500];
 	int32_t n_ir_buffer_length;
 
-	int32_t pn_spo2 = 0;
+	int32_t pn_spo2       = 0;
 	int8_t pch_spo2_valid = 0;
 	int32_t pn_heart_rate = 0;
-	int8_t pch_hr_valid = 0;
+	int8_t pch_hr_valid   = 0;
 
 	size_t ir_len;
 	mp_obj_t *ir_elem;
@@ -41,24 +40,27 @@ mp_maxim_rd177(mp_obj_t ir, mp_obj_t red)
 	}
 
 	n_ir_buffer_length = ir_len;
-	for(size_t i=0; i<ir_len; i++) {
-		pun_ir_buffer[i] = mp_obj_get_int(ir_elem[i]);
+	for (size_t i = 0; i < ir_len; i++) {
+		pun_ir_buffer[i]  = mp_obj_get_int(ir_elem[i]);
 		pun_red_buffer[i] = mp_obj_get_int(red_elem[i]);
 	}
 
-	maxim_heart_rate_and_oxygen_saturation(pun_ir_buffer, n_ir_buffer_length, pun_red_buffer, &pn_spo2, &pch_spo2_valid, &pn_heart_rate, &pch_hr_valid);
+	maxim_heart_rate_and_oxygen_saturation(
+		pun_ir_buffer,
+		n_ir_buffer_length,
+		pun_red_buffer,
+		&pn_spo2,
+		&pch_spo2_valid,
+		&pn_heart_rate,
+		&pch_hr_valid
+	);
 
-	mp_obj_t spo2 = mp_obj_new_int(pn_spo2);
-	mp_obj_t hr = mp_obj_new_int(pn_heart_rate);
+	mp_obj_t spo2       = mp_obj_new_int(pn_spo2);
+	mp_obj_t hr         = mp_obj_new_int(pn_heart_rate);
 	mp_obj_t spo2_valid = mp_obj_new_int(pch_spo2_valid);
-	mp_obj_t hr_valid = mp_obj_new_int(pch_hr_valid);
+	mp_obj_t hr_valid   = mp_obj_new_int(pch_hr_valid);
 
-	mp_obj_t tup[] = {
-		spo2,
-		spo2_valid,
-		hr,
-		hr_valid
-	};
+	mp_obj_t tup[] = { spo2, spo2_valid, hr, hr_valid };
 
 	return mp_obj_new_tuple(4, tup);
 }