diff --git a/src/core/types/decimal192.rs b/src/core/types/decimal192.rs
index 9a79a913d..80ffd2171 100644
--- a/src/core/types/decimal192.rs
+++ b/src/core/types/decimal192.rs
@@ -533,6 +533,11 @@ mod test_inner {
         let sut: SUT = s.parse().unwrap();
         assert_eq!(sut.to_string(), s.to_owned());
     }
+
+    #[test]
+    fn from_str_invalid() {
+        assert_eq!("invalid".parse::<SUT>(), Err(CommonError::DecimalError));
+    }
 }
 
 #[cfg(test)]
diff --git a/src/core/types/locale_config.rs b/src/core/types/locale_config.rs
index 8ff1002a1..453116e71 100644
--- a/src/core/types/locale_config.rs
+++ b/src/core/types/locale_config.rs
@@ -89,4 +89,14 @@ mod tests {
         let sut = LocaleConfig::default();
         assert_eq!(&sut.decimal_separator.unwrap(), ".");
     }
+
+    #[test]
+    fn from_identifier_invalid() {
+        assert_eq!(
+            LocaleConfig::from_identifier("foo"),
+            Err(CommonError::UnrecognizedLocaleIdentifier {
+                bad_value: "foo".to_owned()
+            })
+        );
+    }
 }