diff --git a/src/java.base/share/classes/java/time/chrono/AbstractChronology.java b/src/java.base/share/classes/java/time/chrono/AbstractChronology.java
index acb49a419c4..b2a643d2c81 100644
--- a/src/java.base/share/classes/java/time/chrono/AbstractChronology.java
+++ b/src/java.base/share/classes/java/time/chrono/AbstractChronology.java
@@ -103,6 +103,8 @@
 import java.util.ServiceLoader;
 import java.util.Set;
 import java.util.concurrent.ConcurrentHashMap;
+import org.jspecify.annotations.NullMarked;
+import org.jspecify.annotations.Nullable;
 
 import sun.util.logging.PlatformLogger;
 
@@ -125,6 +127,7 @@
  *
  * @since 1.8
  */
+@NullMarked
 public abstract class AbstractChronology implements Chronology {
 
     /**
@@ -417,7 +420,7 @@ protected AbstractChronology() {
      *  because of a conflict in the input data
      */
     @Override
-    public ChronoLocalDate resolveDate(Map<TemporalField, Long> fieldValues, ResolverStyle resolverStyle) {
+    public @Nullable ChronoLocalDate resolveDate(Map<TemporalField, Long> fieldValues, ResolverStyle resolverStyle) {
         // check epoch-day before inventing era
         if (fieldValues.containsKey(EPOCH_DAY)) {
             return dateEpochDay(fieldValues.remove(EPOCH_DAY));
@@ -678,8 +681,6 @@ public int compareTo(Chronology other) {
      * @return true if this is equal to the other chronology
      */
     @Override
-    
-    
     public boolean equals(@Nullable Object obj) {
         if (this == obj) {
            return true;
diff --git a/src/java.base/share/classes/java/time/chrono/Chronology.java b/src/java.base/share/classes/java/time/chrono/Chronology.java
index f573155ae21..4939f8045ff 100644
--- a/src/java.base/share/classes/java/time/chrono/Chronology.java
+++ b/src/java.base/share/classes/java/time/chrono/Chronology.java
@@ -88,6 +88,8 @@
 import java.util.Map;
 import java.util.Objects;
 import java.util.Set;
+import org.jspecify.annotations.NullMarked;
+import org.jspecify.annotations.Nullable;
 
 /**
  * A calendar system, used to organize and identify dates.
@@ -161,6 +163,7 @@
  *
  * @since 1.8
  */
+@NullMarked
 public interface Chronology extends Comparable<Chronology> {
 
     /**
@@ -295,7 +298,7 @@ static Set<Chronology> getAvailableChronologies() {
      * @return the calendar system type, null if the calendar is not defined by CLDR/LDML
      * @see #getId()
      */
-    String getCalendarType();
+    @Nullable String getCalendarType();
 
     //-----------------------------------------------------------------------
     /**
@@ -684,7 +687,7 @@ public <R> R query(TemporalQuery<R> query) {
      * @throws DateTimeException if the date cannot be resolved, typically
      *  because of a conflict in the input data
      */
-    ChronoLocalDate resolveDate(Map<TemporalField, Long> fieldValues, ResolverStyle resolverStyle);
+    @Nullable ChronoLocalDate resolveDate(Map<TemporalField, Long> fieldValues, ResolverStyle resolverStyle);
 
     //-----------------------------------------------------------------------
     /**
@@ -823,7 +826,7 @@ default boolean isIsoBased() {
      * @return true if this is equal to the other chronology
      */
     @Override
-    boolean equals(Object obj);
+    boolean equals(@Nullable Object obj);
 
     /**
      * A hash code for this chronology.