diff --git a/vlib/strings/builder_c.v b/vlib/strings/builder_c.v
index 8e36e845f7..db197e2a49 100644
--- a/vlib/strings/builder_c.v
+++ b/vlib/strings/builder_c.v
@@ -57,7 +57,7 @@ pub fn (b mut Builder) writeln(s string) {
 
 // buf == 'hello world'
 // last_n(5) returns 'world'
-pub fn (b mut Builder) last_n(n int) string {
+pub fn (b &Builder) last_n(n int) string {
 	if n > b.len {
 		return ''
 	}
@@ -67,7 +67,7 @@ pub fn (b mut Builder) last_n(n int) string {
 
 // buf == 'hello world'
 // after(6) returns 'world'
-pub fn (b mut Builder) after(n int) string {
+pub fn (b &Builder) after(n int) string {
 	if n >= b.len {
 		return ''
 	}
diff --git a/vlib/v/gen/cgen.v b/vlib/v/gen/cgen.v
index 096c99d758..3ba8cc7f3c 100644
--- a/vlib/v/gen/cgen.v
+++ b/vlib/v/gen/cgen.v
@@ -1663,7 +1663,6 @@ fn (g mut Gen) string_inter_literal(node ast.StringInterLiteral) {
 		if i >= node.exprs.len {
 			continue
 		}
-		pos := g.out.len
 		match node.expr_types[i] {
 			table.string_type {
 				g.write('%.*s')
@@ -1679,13 +1678,13 @@ fn (g mut Gen) string_inter_literal(node ast.StringInterLiteral) {
 	for i, expr in node.exprs {
 		if node.expr_types[i] == table.string_type {
 			// `name.str, name.len,`
-			g.expr(node.exprs[i])
+			g.expr(expr)
 			g.write('.len, ')
-			g.expr(node.exprs[i])
+			g.expr(expr)
 			g.write('.str')
 		}
 		else {
-			g.expr(node.exprs[i])
+			g.expr(expr)
 		}
 		if i < node.exprs.len - 1 {
 			g.write(', ')