diff --git a/src/java.base/share/classes/java/time/format/DateTimeParseContext.java b/src/java.base/share/classes/java/time/format/DateTimeParseContext.java
index 0a4c7e825a3b6..b65c9f8ff0ceb 100644
--- a/src/java.base/share/classes/java/time/format/DateTimeParseContext.java
+++ b/src/java.base/share/classes/java/time/format/DateTimeParseContext.java
@@ -345,7 +345,7 @@ TemporalAccessor toResolved(ResolverStyle resolverStyle, Set<TemporalField> reso
      * @return the value mapped to the specified field, null if field was not parsed
      */
     Long getParsed(TemporalField field) {
-        return currentParsed().fieldValues.get(field);
+        return currentParsed().getFieldValue(field);
     }
 
     /**
@@ -362,7 +362,7 @@ Long getParsed(TemporalField field) {
      */
     int setParsedField(TemporalField field, long value, int errorPos, int successPos) {
         Objects.requireNonNull(field, "field");
-        Long old = currentParsed().fieldValues.put(field, value);
+        Long old = currentParsed().putFieldValue(field, value);
         return (old != null && old.longValue() != value) ? ~errorPos : successPos;
     }
 
diff --git a/src/java.base/share/classes/java/time/format/Parsed.java b/src/java.base/share/classes/java/time/format/Parsed.java
index 1ec956dfa2cd3..6a098da2767f6 100644
--- a/src/java.base/share/classes/java/time/format/Parsed.java
+++ b/src/java.base/share/classes/java/time/format/Parsed.java
@@ -87,7 +87,6 @@
 import java.time.Period;
 import java.time.ZoneId;
 import java.time.ZoneOffset;
-import java.time.ZonedDateTime;
 import java.time.chrono.ChronoLocalDate;
 import java.time.chrono.ChronoLocalDateTime;
 import java.time.chrono.ChronoZonedDateTime;
@@ -98,6 +97,7 @@
 import java.time.temporal.TemporalQueries;
 import java.time.temporal.TemporalQuery;
 import java.time.temporal.UnsupportedTemporalTypeException;
+import java.util.EnumMap;
 import java.util.HashMap;
 import java.util.Iterator;
 import java.util.Map;
@@ -128,7 +128,7 @@ final class Parsed implements TemporalAccessor {
     /**
      * The parsed fields.
      */
-    final Map<TemporalField, Long> fieldValues = new HashMap<>();
+    private Map<TemporalField, Long> fieldValues = initFieldValuesMap();
     /**
      * The parsed zone.
      */
@@ -178,6 +178,10 @@ final class Parsed implements TemporalAccessor {
     Parsed copy() {
         // only copy fields used in parsing stage
         Parsed cloned = new Parsed();
+        if (!(fieldValues instanceof EnumMap)) {
+            // Upgrade to a full TemporalField Map
+            cloned.fieldValues = new HashMap<>(this.fieldValues.size());
+        }
         cloned.fieldValues.putAll(this.fieldValues);
         cloned.zone = this.zone;
         cloned.zoneNameType = this.zoneNameType;
@@ -187,6 +191,29 @@ Parsed copy() {
         return cloned;
     }
 
+
+    // A bit contorted way to get the map created.
+    @SuppressWarnings("unchecked")
+    private Map<TemporalField, Long> initFieldValuesMap() {
+        return (Map<TemporalField, Long>) (Object)new EnumMap<ChronoField, Long>(ChronoField.class);
+    }
+
+    Long putFieldValue(TemporalField field, long value) {
+        try {
+            return fieldValues.put(field, value);
+        } catch (ClassCastException cce) {
+            // Upgrade to a full TemporalField Map
+            Map<TemporalField, Long> nmap = new HashMap<>(fieldValues.size() + 1);
+            nmap.putAll(fieldValues);
+            fieldValues = nmap;
+            return nmap.put(field, value);
+        }
+    }
+
+    Long getFieldValue(TemporalField field) {
+        return fieldValues.get(field);
+    }
+
     //-----------------------------------------------------------------------
     @Override
     public boolean isSupported(TemporalField field) {
@@ -334,7 +361,7 @@ private void resolveFields() {
     }
 
     private void updateCheckConflict(TemporalField targetField, TemporalField changeField, Long changeValue) {
-        Long old = fieldValues.put(changeField, changeValue);
+        Long old = putFieldValue(changeField, changeValue);
         if (old != null && old.longValue() != changeValue.longValue()) {
             throw new DateTimeException("Conflict found: " + changeField + " " + old +
                     " differs from " + changeField + " " + changeValue +