diff --git a/modules/parser/src/main/java/org/dhallj/parser/support/ParsingHelpers.java b/modules/parser/src/main/java/org/dhallj/parser/support/ParsingHelpers.java
index cafba16b..c35d7515 100644
--- a/modules/parser/src/main/java/org/dhallj/parser/support/ParsingHelpers.java
+++ b/modules/parser/src/main/java/org/dhallj/parser/support/ParsingHelpers.java
@@ -161,6 +161,11 @@ static final Expr.Parsed makeTimeLiteral(Token token, Token timeZone) {
         boolean positive = timeZone.image.charAt(0) == '+';
         int tzHour = Integer.parseInt(timeZone.image.substring(1, 3));
         int tzMinute = Integer.parseInt(timeZone.image.substring(4, 6));
+
+        if (tzHour > 23 || tzMinute > 59) {
+          throw new ParsingFailure("Invalid temporal literal");
+        }
+
         int seconds = tzHour * 60 + tzMinute;
         value = positive ? seconds : -seconds;
       } else {
@@ -212,6 +217,11 @@ static final Expr.Parsed makeDateTimeLiteral(Token token, Token timeZone) {
         boolean positive = timeZone.image.charAt(0) == '+';
         int tzHour = Integer.parseInt(timeZone.image.substring(1, 3));
         int tzMinute = Integer.parseInt(timeZone.image.substring(4, 6));
+
+        if (tzHour > 23 || tzMinute > 59) {
+          throw new ParsingFailure("Invalid temporal literal");
+        }
+
         int seconds = tzHour * 60 + tzMinute;
         value = positive ? seconds : -seconds;
       } else {
diff --git a/tests/src/test/scala/org/dhallj/tests/MiscSuite.scala b/tests/src/test/scala/org/dhallj/tests/MiscSuite.scala
index 50c53ea4..9cbcb2d5 100644
--- a/tests/src/test/scala/org/dhallj/tests/MiscSuite.scala
+++ b/tests/src/test/scala/org/dhallj/tests/MiscSuite.scala
@@ -40,16 +40,21 @@ class MiscSuite extends ScalaCheckSuite {
       val parts = asString.split("-")
 
       // We need a reasonable four-digit year.
-      val cleaned = if (parts(0).isEmpty) {
-        // If it's negative we just make something up.
-        "2021" + "-" + parts.drop(2).mkString("-")
-      } else if (parts(0).size != 4) {
-        // If it's not four digits we just make something up.
-        "1999" + "-" + parts.drop(1).mkString("-")
-      } else {
-        asString
-      }
+      val cleaned = (
+        if (parts(0).isEmpty) {
+          // If it's negative we just make something up.
+          "2021" + "-" + parts.drop(2).mkString("-")
+        } else if (parts(0).size != 4) {
+          // If it's not four digits we just make something up.
+          "1999" + "-" + parts.drop(1).mkString("-")
+        } else {
+          asString
+        }
+        // The ScalaCheck instance produces instants that can't be parsed.
+      ).replaceAll("-02-29", "-02-28")
+
       val expected = Instant.parse(cleaned)
+
       val result = Decode.decode(DhallParser.parse(cleaned).getEncodedBytes).toString
 
       // Keep it low-tech.