diff --git a/lib/runtime.asm b/lib/runtime.asm
index 974fbe1..4422045 100644
--- a/lib/runtime.asm
+++ b/lib/runtime.asm
@@ -23,6 +23,7 @@ _start:
 
 	# call main
 	jal main
+	nop
 
 	# exit
 	move	$a0, $v0
diff --git a/test/masm/fncall.asm b/test/masm/fncall.asm
index 96d1ba2..39455ab 100644
--- a/test/masm/fncall.asm
+++ b/test/masm/fncall.asm
@@ -11,6 +11,7 @@ result:
 	move	$t0, $a0
 	move	$v0, $t0
 	jr	$ra
+	nop
 
 main:
 	# save ra on stack
@@ -20,6 +21,7 @@ main:
 	# set return to 17
 	li	$a0, 17
 	jal	result
+	nop
 
 	# pop ra from stack
 	lw	$ra, 0($sp)
@@ -27,3 +29,4 @@ main:
 
 	# return result
 	jr	$ra
+	nop
diff --git a/test/masm/div.asm b/test/masm/fpe.asm
similarity index 97%
rename from test/masm/div.asm
rename to test/masm/fpe.asm
index b9b4f3f..a3725d5 100644
--- a/test/masm/div.asm
+++ b/test/masm/fpe.asm
@@ -15,3 +15,4 @@ main:
 	# return
 	li	$v0, 0
 	jr	$ra
+	nop
diff --git a/test/masm/hello.asm b/test/masm/hello.asm
index 2d64ae5..3819b2a 100644
--- a/test/masm/hello.asm
+++ b/test/masm/hello.asm
@@ -24,3 +24,4 @@ main:
 	# return 1
 	li	$v0, 0
 	jr	$ra
+	nop
diff --git a/test/masm/recursion.asm b/test/masm/recursion.asm
new file mode 100644
index 0000000..38982e1
--- /dev/null
+++ b/test/masm/recursion.asm
@@ -0,0 +1,41 @@
+# Copyright (c) 2024 Freya Murphy
+
+# file: recursion.asm
+# test: should recurse sum n..0 numbers
+
+.text
+.align 2
+.globl main
+
+main:
+	# init $a0
+	li	$a0, 5
+
+sum:
+	# save stack
+	addiu	$sp, $sp, -8
+	sw	$ra, 0($sp)
+	sw	$s0, 4($sp)
+
+	# load n from a0
+	move	$s0, $a0
+
+	# skip if n is zero
+	li	$v0, 0
+	beq	$s0, $zero, add
+	nop
+	jal	sum
+	addi	$a0, $s0, -1
+
+add:
+	# n = n + returned
+	add	$v0, $s0, $v0
+
+	# restore stack
+	lw	$ra, 0($sp)
+	lw	$s0, 4($sp)
+	addiu	$sp, $sp, 8
+
+	# return
+	jr	$ra
+	nop
diff --git a/test/masm/fault.asm b/test/masm/segv.asm
similarity index 97%
rename from test/masm/fault.asm
rename to test/masm/segv.asm
index df700cf..4102bc2 100644
--- a/test/masm/fault.asm
+++ b/test/masm/segv.asm
@@ -13,3 +13,4 @@ main:
 	# return
 	li	$v0, 0
 	jr	$ra
+	nop
diff --git a/test/out/div b/test/out/fpe
similarity index 89%
rename from test/out/div
rename to test/out/fpe
index 94b9ab8..e6aeb31 100644
--- a/test/out/div
+++ b/test/out/fpe
@@ -12,4 +12,4 @@ $v1:	0x00000000 $t3:	0x00000000 $s3:	0x00000000 $k1:	0x00000000
 $a0:	0x00000000 $t4:	0x00000000 $s4:	0x00000000 $gp:	0x00000000
 $a1:	0x00000000 $t5:	0x00000000 $s5:	0x00000000 $sp:	0x10001000
 $a2:	0x00000000 $t6:	0x00000000 $s6:	0x00000000 $fp:	0x00000000
-$a3:	0x00000000 $t7:	0x00000000 $s7:	0x00000000 $ra:	0x0040001c
+$a3:	0x00000000 $t7:	0x00000000 $s7:	0x00000000 $ra:	0x00400024
diff --git a/test/out/div.status b/test/out/fpe.status
similarity index 100%
rename from test/out/div.status
rename to test/out/fpe.status
diff --git a/test/out/recursion b/test/out/recursion
new file mode 100644
index 0000000..e69de29
diff --git a/test/out/recursion.status b/test/out/recursion.status
new file mode 100644
index 0000000..60d3b2f
--- /dev/null
+++ b/test/out/recursion.status
@@ -0,0 +1 @@
+15
diff --git a/test/out/fault b/test/out/segv
similarity index 90%
rename from test/out/fault
rename to test/out/segv
index 938bb46..1796539 100644
--- a/test/out/fault
+++ b/test/out/segv
@@ -12,4 +12,4 @@ $v1:	0x00000000 $t3:	0x00000000 $s3:	0x00000000 $k1:	0x00000000
 $a0:	0x00000000 $t4:	0x00000000 $s4:	0x00000000 $gp:	0x00000000
 $a1:	0x00000000 $t5:	0x00000000 $s5:	0x00000000 $sp:	0x10001000
 $a2:	0x00000000 $t6:	0x00000000 $s6:	0x00000000 $fp:	0x00000000
-$a3:	0x00000000 $t7:	0x00000000 $s7:	0x00000000 $ra:	0x00400018
+$a3:	0x00000000 $t7:	0x00000000 $s7:	0x00000000 $ra:	0x00400020
diff --git a/test/out/fault.status b/test/out/segv.status
similarity index 100%
rename from test/out/fault.status
rename to test/out/segv.status