diff --git a/src/format/strftime.rs b/src/format/strftime.rs
index 2fd6da0351..2a21be98d0 100644
--- a/src/format/strftime.rs
+++ b/src/format/strftime.rs
@@ -755,9 +755,9 @@ fn test_strftime_docs() {
     assert_eq!(dt.format("%%").unwrap().to_string(), "%");
 
     // complex format specifiers
-    assert_eq!(dt.format("  %Y%d%m%%%%%t%H%M%S\t").to_string(), "  20010807%%\t003460\t");
+    assert_eq!(dt.format("  %Y%d%m%%%%%t%H%M%S\t").unwrap().to_string(), "  20010807%%\t003460\t");
     assert_eq!(
-        dt.format("  %Y%d%m%%%%%t%H:%P:%M%S%:::z\t").to_string(),
+        dt.format("  %Y%d%m%%%%%t%H:%P:%M%S%:::z\t").unwrap().to_string(),
         "  20010807%%\t00:am:3460+09\t"
     );
 }
diff --git a/src/naive/datetime/tests.rs b/src/naive/datetime/tests.rs
index 76d2adff13..be9df12916 100644
--- a/src/naive/datetime/tests.rs
+++ b/src/naive/datetime/tests.rs
@@ -20,7 +20,7 @@ fn test_datetime_from_timestamp_millis() {
     for (timestamp_millis, formatted) in valid_map.iter().copied() {
         let naive_datetime = NaiveDateTime::from_timestamp_millis(timestamp_millis);
         assert_eq!(timestamp_millis, naive_datetime.unwrap().timestamp_millis());
-        assert_eq!(naive_datetime.unwrap().format("%F %T%.9f").to_string(), formatted);
+        assert_eq!(naive_datetime.unwrap().format("%F %T%.9f").unwrap().to_string(), formatted);
     }
 
     let invalid = [i64::MAX, i64::MIN];
@@ -57,7 +57,7 @@ fn test_datetime_from_timestamp_micros() {
     for (timestamp_micros, formatted) in valid_map.iter().copied() {
         let naive_datetime = NaiveDateTime::from_timestamp_micros(timestamp_micros);
         assert_eq!(timestamp_micros, naive_datetime.unwrap().timestamp_micros());
-        assert_eq!(naive_datetime.unwrap().format("%F %T%.9f").to_string(), formatted);
+        assert_eq!(naive_datetime.unwrap().format("%F %T%.9f").unwrap().to_string(), formatted);
     }
 
     let invalid = [i64::MAX, i64::MIN];
diff --git a/tests/dateutils.rs b/tests/dateutils.rs
index aabab29a78..a9b2d566e2 100644
--- a/tests/dateutils.rs
+++ b/tests/dateutils.rs
@@ -110,7 +110,7 @@ fn verify_against_date_command_format_local(path: &'static str, dt: NaiveDateTim
     let ldt = Local
         .from_local_datetime(&date.and_hms_opt(dt.hour(), dt.minute(), dt.second()).unwrap())
         .unwrap();
-    let formated_date = format!("{}\n", ldt.format(required_format));
+    let formated_date = format!("{}\n", ldt.format(required_format).unwrap());
     assert_eq!(date_command_str, formated_date);
 }