diff --git a/vlib/compiler/fn.v b/vlib/compiler/fn.v
index 835e5b67d5..a8c9319b25 100644
--- a/vlib/compiler/fn.v
+++ b/vlib/compiler/fn.v
@@ -756,7 +756,7 @@ fn (p mut Parser) fn_call(f mut Fn, method_ph int, receiver_var, receiver_type s
 				// probably a typo, do not concern the user with the above error message
 				break
 			}
-			i += 1
+			i++
 		}
 	}
 	// if p.pref.is_prof {
@@ -1271,7 +1271,7 @@ fn (p mut Parser) extract_type_inst(f &Fn, args_ []string) TypeInst {
 				if fa == tp {
 					r.inst[tp] = fa
 					found = true
-					i += 1
+					i++
 					break
 				}
 			}
@@ -1287,7 +1287,7 @@ fn (p mut Parser) extract_type_inst(f &Fn, args_ []string) TypeInst {
 		}
 		// println("extracted $tp => $ti")
 		r.inst[tp] = ti
-		i += 1
+		i++
 		if i >= f.type_pars.len { break }
 	}
 	if r.inst[f.typ] == '' && f.typ in f.type_pars {
diff --git a/vlib/compiler/parser.v b/vlib/compiler/parser.v
index bd8b9f867c..3b970c511f 100644
--- a/vlib/compiler/parser.v
+++ b/vlib/compiler/parser.v
@@ -1385,6 +1385,10 @@ fn ($v.name mut $v.typ) $p.cur_fn.name (...) {
 			p.gen('= ustring_add($v.name, ')
 		}
 		else {
+			next := p.peek_token()
+			if next.tok == .number  && next.lit== '1' {
+				p.warn('use ++ instead of += 1')
+			}
 			p.gen(' += ')
 		}
 	}
diff --git a/vlib/compiler/scanner.v b/vlib/compiler/scanner.v
index b3eaa356fe..a28e27fc58 100644
--- a/vlib/compiler/scanner.v
+++ b/vlib/compiler/scanner.v
@@ -644,8 +644,7 @@ fn (s mut Scanner) scan() ScanRes {
 			return s.end_of_file()
 		}
 	}
-	mut msg := 'invalid character `${c.str()}`'
-	s.error(msg)
+	s.error('invalid character `${c.str()}`')
 	return s.end_of_file()
 }
 
diff --git a/vlib/strings/builder_c.v b/vlib/strings/builder_c.v
index 82656be7b9..2b8298d6c7 100644
--- a/vlib/strings/builder_c.v
+++ b/vlib/strings/builder_c.v
@@ -19,14 +19,14 @@ pub fn new_builder(initial_size int) Builder {
 
 pub fn (b mut Builder) write_b(data byte) {
 	b.buf << data
-	b.len += 1
+	b.len++
 }
 
 pub fn (b mut Builder) write(s string) {
 	b.buf.push_many(s.str, s.len)
 	//for c in s {
 		//b.buf << c
-	//}	
+	//}
 	//b.buf << []byte(s)  // TODO
 	b.len += s.len
 }
@@ -34,7 +34,7 @@ pub fn (b mut Builder) write(s string) {
 pub fn (b mut Builder) writeln(s string) {
 	//for c in s {
 		//b.buf << c
-	//}	
+	//}
 	b.buf.push_many(s.str, s.len)
 	//b.buf << []byte(s)  // TODO
 	b.buf << `\n`