diff --git a/crates/jrsonnet-evaluator/src/builtin/manifest.rs b/crates/jrsonnet-evaluator/src/builtin/manifest.rs
index a5a6827d..47dfae3b 100644
--- a/crates/jrsonnet-evaluator/src/builtin/manifest.rs
+++ b/crates/jrsonnet-evaluator/src/builtin/manifest.rs
@@ -189,40 +189,19 @@ fn yaml_needs_quotes(string: &str) -> bool {
 		string.starts_with(' ') || string.ends_with(' ')
 	}
 
-	string == ""
+	string.is_empty()
 		|| need_quotes_spaces(string)
-		|| string.starts_with(|character: char| match character {
-			'&' | '*' | '?' | '|' | '-' | '<' | '>' | '=' | '!' | '%' | '@' => true,
-			_ => false,
-		}) || string.contains(|character: char| match character {
-		':'
-		| '{'
-		| '}'
-		| '['
-		| ']'
-		| ','
-		| '#'
-		| '`'
-		| '\"'
-		| '\''
-		| '\\'
-		| '\0'..='\x06'
-		| '\t'
-		| '\n'
-		| '\r'
-		| '\x0e'..='\x1a'
-		| '\x1c'..='\x1f' => true,
-		_ => false,
-	}) || [
-		// http://yaml.org/type/bool.html
-		// Note: 'y', 'Y', 'n', 'N', is not quoted deliberately, as in libyaml. PyYAML also parse
-		// them as string, not booleans, although it is violating the YAML 1.1 specification.
-		// See https://github.com/dtolnay/serde-yaml/pull/83#discussion_r152628088.
-		"yes", "Yes", "YES", "no", "No", "NO", "True", "TRUE", "true", "False", "FALSE", "false",
-		"on", "On", "ON", "off", "Off", "OFF", // http://yaml.org/type/null.html
-		"null", "Null", "NULL", "~",
-	]
-	.contains(&string)
+		|| string.starts_with(|c| matches!(c, '&' | '*' | '?' | '|' | '-' | '<' | '>' | '=' | '!' | '%' | '@'))
+		|| string.contains(|c| matches!(c, ':' | '{' | '}' | '[' | ']' | ',' | '#' | '`' | '\"' | '\'' | '\\' | '\0'..='\x06' | '\t' | '\n' | '\r' | '\x0e'..='\x1a' | '\x1c'..='\x1f'))
+		|| [
+			// http://yaml.org/type/bool.html
+			// Note: 'y', 'Y', 'n', 'N', is not quoted deliberately, as in libyaml. PyYAML also parse
+			// them as string, not booleans, although it is violating the YAML 1.1 specification.
+			// See https://github.com/dtolnay/serde-yaml/pull/83#discussion_r152628088.
+			"yes", "Yes", "YES", "no", "No", "NO", "True", "TRUE", "true", "False", "FALSE", "false",
+			"on", "On", "ON", "off", "Off", "OFF", // http://yaml.org/type/null.html
+			"null", "Null", "NULL", "~",
+		].contains(&string)
 		|| (string.chars().all(|c| matches!(c, '0'..='9' | '-'))
 			&& string.chars().filter(|c| *c == '-').count() == 2)
 		|| string.starts_with('.')
@@ -262,8 +241,8 @@ fn manifest_yaml_ex_buf(
 					buf.push_str(options.padding);
 					buf.push_str(line);
 				}
-			} else if !options.quote_keys && !yaml_needs_quotes(&s) {
-				buf.push_str(&s);
+			} else if !options.quote_keys && !yaml_needs_quotes(s) {
+				buf.push_str(s);
 			} else {
 				escape_string_json_buf(s, buf);
 			}
@@ -311,8 +290,8 @@ fn manifest_yaml_ex_buf(
 						buf.push('\n');
 						buf.push_str(cur_padding);
 					}
-					if !options.quote_keys && !yaml_needs_quotes(&key) {
-						buf.push_str(&key);
+					if !options.quote_keys && !yaml_needs_quotes(key) {
+						buf.push_str(key);
 					} else {
 						escape_string_json_buf(key, buf);
 					}