diff --git a/vlib/sync/channels.v b/vlib/sync/channels.v
index 7fc11b5d5d..74b8bd4852 100644
--- a/vlib/sync/channels.v
+++ b/vlib/sync/channels.v
@@ -121,15 +121,19 @@ pub:
 
 pub fn new_channel<T>(n u32) &Channel {
 	st := sizeof(T)
-	return new_channel_st(n, st)
+	if isreftype(T) {
+		return new_channel_st(n, st)
+	} else {
+		return new_channel_st_noscan(n, st)
+	}
 }
 
 fn new_channel_st(n u32, st u32) &Channel {
 	wsem := if n > 0 { n } else { 1 }
 	rsem := if n > 0 { u32(0) } else { 1 }
 	rbuf := if n > 0 { unsafe { malloc(int(n * st)) } } else { &byte(0) }
-	sbuf := if n > 0 { vcalloc(int(n * 2)) } else { &byte(0) }
-	mut ch := &Channel{
+	sbuf := if n > 0 { vcalloc_noscan(int(n * 2)) } else { &byte(0) }
+	mut ch := Channel{
 		objsize: st
 		cap: n
 		write_free: n
@@ -143,7 +147,33 @@ fn new_channel_st(n u32, st u32) &Channel {
 	ch.readsem.init(rsem)
 	ch.writesem_im.init(0)
 	ch.readsem_im.init(0)
-	return ch
+	return &ch
+}
+
+fn new_channel_st_noscan(n u32, st u32) &Channel {
+	$if gcboehm_opt ? {
+		wsem := if n > 0 { n } else { 1 }
+		rsem := if n > 0 { u32(0) } else { 1 }
+		rbuf := if n > 0 { unsafe { malloc_noscan(int(n * st)) } } else { &byte(0) }
+		sbuf := if n > 0 { vcalloc_noscan(int(n * 2)) } else { &byte(0) }
+		mut ch := Channel{
+			objsize: st
+			cap: n
+			write_free: n
+			read_avail: 0
+			ringbuf: rbuf
+			statusbuf: sbuf
+			write_subscriber: 0
+			read_subscriber: 0
+		}
+		ch.writesem.init(wsem)
+		ch.readsem.init(rsem)
+		ch.writesem_im.init(0)
+		ch.readsem_im.init(0)
+		return &ch
+	} $else {
+		return new_channel_st(n, st)
+	}
 }
 
 pub fn (ch &Channel) auto_str(typename string) string {
diff --git a/vlib/sync/pool/pool.v b/vlib/sync/pool/pool.v
index 7171d3a73a..b2c5340cdd 100644
--- a/vlib/sync/pool/pool.v
+++ b/vlib/sync/pool/pool.v
@@ -45,7 +45,7 @@ pub fn new_pool_processor(context PoolProcessorConfig) &PoolProcessor {
 	if isnil(context.callback) {
 		panic('You need to pass a valid callback to new_pool_processor.')
 	}
-	mut pool := &PoolProcessor{
+	mut pool := PoolProcessor{
 		items: []
 		results: []
 		shared_context: voidptr(0)
@@ -55,7 +55,7 @@ pub fn new_pool_processor(context PoolProcessorConfig) &PoolProcessor {
 		thread_cb: voidptr(context.callback)
 	}
 	pool.waitgroup.init()
-	return pool
+	return &pool
 }
 
 // set_max_jobs gives you the ability to override the number
diff --git a/vlib/sync/waitgroup.v b/vlib/sync/waitgroup.v
index e9b3d170e6..ffa9af52c0 100644
--- a/vlib/sync/waitgroup.v
+++ b/vlib/sync/waitgroup.v
@@ -26,9 +26,9 @@ mut:
 }
 
 pub fn new_waitgroup() &WaitGroup {
-	mut wg := &WaitGroup{}
+	mut wg := WaitGroup{}
 	wg.init()
-	return wg
+	return &wg
 }
 
 pub fn (mut wg WaitGroup) init() {
diff --git a/vlib/v/gen/c/cgen.v b/vlib/v/gen/c/cgen.v
index 7d340bf7e7..6b66904f44 100644
--- a/vlib/v/gen/c/cgen.v
+++ b/vlib/v/gen/c/cgen.v
@@ -3116,7 +3116,8 @@ fn (mut g Gen) expr(node ast.Expr) {
 		}
 		ast.ChanInit {
 			elem_typ_str := g.typ(node.elem_type)
-			g.write('sync__new_channel_st(')
+			noscan := g.check_noscan(node.elem_type)
+			g.write('sync__new_channel_st${noscan}(')
 			if node.has_cap {
 				g.expr(node.cap_expr)
 			} else {
@@ -6074,8 +6075,10 @@ fn (mut g Gen) type_default(typ_ ast.Type) string {
 			return g.type_default((sym.info as ast.Alias).parent_type)
 		}
 		.chan {
-			elemtypstr := g.typ(sym.chan_info().elem_type)
-			return 'sync__new_channel_st(0, sizeof($elemtypstr))'
+			elem_type := sym.chan_info().elem_type
+			elemtypstr := g.typ(elem_type)
+			noscan := g.check_noscan(elem_type)
+			return 'sync__new_channel_st${noscan}(0, sizeof($elemtypstr))'
 		}
 		.array {
 			elem_typ := sym.array_info().elem_type
diff --git a/vlib/v/markused/markused.v b/vlib/v/markused/markused.v
index 989d41c6f7..3bb1922280 100644
--- a/vlib/v/markused/markused.v
+++ b/vlib/v/markused/markused.v
@@ -56,6 +56,7 @@ pub fn mark_used(mut table ast.Table, pref &pref.Preferences, ast_files []&ast.F
 		// string. methods
 		'18.add',
 		'18.trim_space',
+		'18.repeat',
 		'18.replace',
 		'18.clone',
 		'18.clone_static',
@@ -302,6 +303,14 @@ pub fn mark_used(mut table ast.Table, pref &pref.Preferences, ast_files []&ast.F
 				|| k.starts_with('map_') {
 				walker.fn_decl(mut mfn)
 			}
+			if pref.gc_mode in [.boehm_full_opt, .boehm_incr_opt] {
+				if k in ['new_map_noscan_key', 'new_map_noscan_value', 'new_map_noscan_key_value',
+					'new_map_init_noscan_key', 'new_map_init_noscan_value',
+					'new_map_init_noscan_key_value',
+				] {
+					walker.fn_decl(mut mfn)
+				}
+			}
 		}
 	} else {
 		for map_fn_name in ['new_map', 'new_map_init', 'map_hash_string', 'new_dense_array'] {