diff --git a/tools/fast/fast.v b/tools/fast/fast.v
index 2c7b426f7d..04e9642b99 100644
--- a/tools/fast/fast.v
+++ b/tools/fast/fast.v
@@ -11,22 +11,26 @@ fn main() {
 	vdir := os.dir(os.dir(dir))
 	if !os.exists('$vdir/v') && !os.is_dir('$vdir/vlib') {
 		println('fast.html generator needs to be located in `v/tools/fast/`')
-	}	
+	}
 	println('fast.html generator\n')
 	// Fetch the last commit's hash
 	println('Fetching updates...')
-	exec('git pull --rebase')
+	ret := os.system('git pull --rebase')
+	if ret != 0 {
+		println('failed to git pull')
+		return
+	}
 	mut commit_hash := exec('git rev-parse HEAD')
 	commit_hash = commit_hash[..7]
 	if !os.exists('table.html') {
 		os.create('table.html') or { panic(err) }
-	}	
+	}
 	mut table := os.read_file('table.html') or { panic(err) }
 	// Do nothing if it's already been processed.
 	if table.contains(commit_hash) {
 		println('Commit $commit_hash has already been processed')
 		return
-	}	
+	}
 	// Build an optimized V
 	println('Building vprod...')
 	exec('v -o $vdir/vprod -prod $vdir/v.v')
@@ -74,7 +78,7 @@ fn measure(cmd string) int {
 	println('Warming up...')
 	for i in 0..3 {
 		exec(cmd)
-	}	
+	}
 	println('Building...')
 	ticks := time.ticks()
 	exec(cmd)
diff --git a/tools/fast/header.html b/tools/fast/header.html
index 700b65408d..e3e1fc8f86 100644
--- a/tools/fast/header.html
+++ b/tools/fast/header.html
@@ -38,7 +38,7 @@ td {
 <h2>Is V still fast?</h2>
 
 Monitoring compilation speed for each commit. <br><br>
-Running on a $3.5 instance. <br><br>
+Running on a 2014 MacBook Pro. <br><br>
 Source code: <a target=blank href='https://github.com/vlang/v/blob/master/tools/fast/fast.v'>fast.v</a> <br><br>
 
 <table>
diff --git a/vlib/builtin/array.v b/vlib/builtin/array.v
index 997497dca7..35aa5b15ee 100644
--- a/vlib/builtin/array.v
+++ b/vlib/builtin/array.v
@@ -18,11 +18,12 @@ pub:
 
 // Private function, used by V (`nums := []int`)
 fn new_array(mylen, cap, elm_size int) array {
+	cap_ := if cap == 0 { 1 } else { cap }
 	arr := array {
 		len: mylen
 		cap: cap
 		element_size: elm_size
-		data: calloc(cap * elm_size)
+		data: calloc(cap_ * elm_size)
 	}
 	return arr
 }
@@ -36,11 +37,12 @@ pub fn make(len, cap, elm_size int) array {
 
 // Private function, used by V (`nums := [1, 2, 3]`)
 fn new_array_from_c_array(len, cap, elm_size int, c_array voidptr) array {
+	cap_ := if cap == 0 { 1 } else { cap }
 	arr := array {
 		len: len
 		cap: cap
 		element_size: elm_size
-		data: calloc(cap * elm_size)
+		data: calloc(cap_ * elm_size)
 	}
 	// TODO Write all memory functions (like memcpy) in V
 	C.memcpy(arr.data, c_array, len * elm_size)
@@ -96,11 +98,15 @@ pub fn (a array) repeat(nr_repeats int) array {
 	if nr_repeats < 0 {
 		panic('array.repeat: count is negative (count == $nr_repeats)')
 	}
+	mut size := nr_repeats * a.len * a.element_size
+	if size == 0 {
+		size = a.element_size
+	}
 	arr := array {
 		len: nr_repeats * a.len
 		cap: nr_repeats * a.len
 		element_size: a.element_size
-		data: calloc(nr_repeats * a.len * a.element_size)
+		data: calloc(size)
 	}
 	for i := 0; i < nr_repeats; i++ {
 		C.memcpy(arr.data + i * a.len * a.element_size, a.data, a.len * a.element_size)
@@ -267,11 +273,15 @@ pub fn (a array) reverse() array {
 
 // array.clone returns an independent copy of a given array
 pub fn (a array) clone() array {
+	mut size := a.cap * a.element_size
+	if size == 0 {
+		size++
+	}
 	arr := array {
 		len: a.len
 		cap: a.cap
 		element_size: a.element_size
-		data: calloc(a.cap * a.element_size)
+		data: calloc(size)
 	}
 	C.memcpy(arr.data, a.data, a.cap * a.element_size)
 	return arr
diff --git a/vlib/builtin/builtin.v b/vlib/builtin/builtin.v
index 8bc049bcf8..e1f6f2268c 100644
--- a/vlib/builtin/builtin.v
+++ b/vlib/builtin/builtin.v
@@ -106,7 +106,7 @@ __global nr_mallocs int = 0
 [unsafe_fn]
 pub fn malloc(n int) byteptr {
 	if n <= 0 {
-		panic('malloc(<0)')
+		panic('malloc(<=0)')
 	}
 	$if prealloc {
 		res := g_m2_ptr
@@ -136,8 +136,8 @@ TODO
 }
 
 pub fn calloc(n int) byteptr {
-	if n < 0 {
-		panic('calloc(<0)')
+	if n <= 0 {
+		panic('calloc(<=0)')
 	}
 	return C.calloc(n, 1)
 }
diff --git a/vlib/builtin/option.v b/vlib/builtin/option.v
index 104e761089..91137c8fac 100644
--- a/vlib/builtin/option.v
+++ b/vlib/builtin/option.v
@@ -4,6 +4,16 @@
 
 module builtin
 
+/*
+struct Option2<T> {
+	data T
+	error string
+	ecode int
+	ok bool
+	is_none bool
+}
+*/
+
 struct Option {
 	data     [300]byte
 	error    string
diff --git a/vlib/compiler/fn.v b/vlib/compiler/fn.v
index ed11982173..eed86f6416 100644
--- a/vlib/compiler/fn.v
+++ b/vlib/compiler/fn.v
@@ -403,6 +403,7 @@ fn (p mut Parser) fn_decl() {
 	// Register ?option type for return value and args
 	if typ.starts_with('Option_') {
 		p.cgen.typedefs << 'typedef Option $typ;'
+		//p.cgen.typedefs << 'typedef struct Option_$typ Option_$typ'
 	}
 	for arg in f.args {
 		if arg.typ.starts_with('Option_') {