diff --git a/gradle/wrapper/gradle-wrapper.properties b/gradle/wrapper/gradle-wrapper.properties
index 0e680f3..68ca99a 100644
--- a/gradle/wrapper/gradle-wrapper.properties
+++ b/gradle/wrapper/gradle-wrapper.properties
@@ -2,4 +2,4 @@ distributionBase=GRADLE_USER_HOME
 distributionPath=wrapper/dists
 zipStoreBase=GRADLE_USER_HOME
 zipStorePath=wrapper/dists
-distributionUrl=https\://services.gradle.org/distributions/gradle-4.3.1-bin.zip
+distributionUrl=https\://services.gradle.org/distributions/gradle-6.8.3-bin.zip
diff --git a/timeseries/src/main/java/com/github/signaflo/timeseries/TimePeriod.java b/timeseries/src/main/java/com/github/signaflo/timeseries/TimePeriod.java
index 980cf03..d0bd647 100644
--- a/timeseries/src/main/java/com/github/signaflo/timeseries/TimePeriod.java
+++ b/timeseries/src/main/java/com/github/signaflo/timeseries/TimePeriod.java
@@ -33,8 +33,8 @@
  */
 public final class TimePeriod {
 
-    private final TimeUnit timeUnit;
-    private final long periodLength;
+    public final TimeUnit timeUnit;
+    public final long periodLength;
 
     /**
      * Create a new time period with the given unit of time and period length.
diff --git a/timeseries/src/main/java/com/github/signaflo/timeseries/TimeUnit.java b/timeseries/src/main/java/com/github/signaflo/timeseries/TimeUnit.java
index d9f0a7f..99417e2 100644
--- a/timeseries/src/main/java/com/github/signaflo/timeseries/TimeUnit.java
+++ b/timeseries/src/main/java/com/github/signaflo/timeseries/TimeUnit.java
@@ -50,8 +50,8 @@ public enum TimeUnit {
     MICROSECOND(ChronoUnit.MICROS, 1L),
     NANOSECOND(ChronoUnit.NANOS, 1L);
 
-    private final TemporalUnit temporalUnit;
-    private final long unitLength;
+    public final TemporalUnit temporalUnit;
+    public final long unitLength;
 
     TimeUnit(final TemporalUnit timeUnit, final long unitLength) {
         this.temporalUnit = timeUnit;