diff --git a/lab-1/fib.s b/lab-1/fib.s
index 14c6734..1abbf02 100644
--- a/lab-1/fib.s
+++ b/lab-1/fib.s
@@ -15,19 +15,23 @@ fibonacci:
 
 	@ R4 = R0 - 0 (update flags)
 	@ if(R0 <= 0) goto .L3 (which returns 0)
-
+	subs r4, r0, #0
+	ble .L3
 	@ Compare R4 wtih 1
 	@ If R4 == 1 goto .L4 (which returns 1)
-
+	subs r0, r4, #1
+	beq .L4
 	@ R0 = R4 - 1
 	@ Recursive call to fibonacci with R4 - 1 as parameter
-
+	bl fibonacci
 	@ R5 = R0
 	@ R0 = R4 - 2
 	@ Recursive call to fibonacci with R4 - 2 as parameter
-
+	mov r5, r0
+	sub r0, r4, #2
+	bl fibonacci
 	@ R0 = R5 + R0 (update flags)
-
+	adds r0, r0, r5
 	pop {r3, r4, r5, pc}		@EPILOG
 
 	@ END CODE MODIFICATION
diff --git a/lab-2/mutex.s b/lab-2/mutex.s
index d23565d..aa2d346 100644
--- a/lab-2/mutex.s
+++ b/lab-2/mutex.s
@@ -8,10 +8,21 @@
 	.global lock_mutex
 	.type lock_mutex, function
 lock_mutex:
-        @ INSERT CODE BELOW
-
-        @ END CODE INSERT
+	@ INSERT CODE BELOW
+	ldr r1, =locked
+.L1:
+	ldrex r2, [r0]
+	cmp r2, #0
+	bne .L2
+	strex r2, r1, [r0]
+	cmp r2, #0
+	beq .L1
+	dmb
 	bx lr
+.L2:
+	wfe
+	b .L1
+	@ END CODE INSERT
 
 	.size lock_mutex, .-lock_mutex
 
@@ -19,8 +30,12 @@ lock_mutex:
 	.type unlock_mutex, function
 unlock_mutex:
 	@ INSERT CODE BELOW
-        
-        @ END CODE INSERT
+	ldr r1, =unlocked
+	dmb
+	str r1, [r0]
+	dsb
+	sev
+	@ END CODE INSERT
 	bx lr
 	.size unlock_mutex, .-unlock_mutex