diff --git a/src/main/java/org/jsoup/internal/SharedConstants.java b/src/main/java/org/jsoup/internal/SharedConstants.java
index 141e1df9a8..b0f490ca6d 100644
--- a/src/main/java/org/jsoup/internal/SharedConstants.java
+++ b/src/main/java/org/jsoup/internal/SharedConstants.java
@@ -11,6 +11,7 @@ public final class SharedConstants {
     public static final String EndRangeKey = "jsoup.end";
 
     public static final int DefaultBufferSize = 1024 * 32;
+    public static final int HashPrime = 31;
 
     private SharedConstants() {}
 }
diff --git a/src/main/java/org/jsoup/nodes/Attributes.java b/src/main/java/org/jsoup/nodes/Attributes.java
index ff2f0b995e..86a2e27870 100644
--- a/src/main/java/org/jsoup/nodes/Attributes.java
+++ b/src/main/java/org/jsoup/nodes/Attributes.java
@@ -555,20 +555,34 @@ public int deduplicate(ParseSettings settings) {
             return 0;
         boolean preserve = settings.preserveAttributeCase();
         int dupes = 0;
-        OUTER: for (int i = 0; i < keys.length; i++) {
-            for (int j = i + 1; j < keys.length; j++) {
-                if (keys[j] == null)
-                    continue OUTER; // keys.length doesn't shrink when removing, so re-test
-                if ((preserve && keys[i].equals(keys[j])) || (!preserve && keys[i].equalsIgnoreCase(keys[j]))) {
-                    dupes++;
-                    remove(j);
-                    j--;
-                }
+
+        for (int i = 0; i < keys.length; i++) {
+            dupes += removeDuplicatesFrom(i, preserve);
+        }
+
+        return dupes;
+    }
+
+    private int removeDuplicatesFrom(int index, boolean preserve) {
+        int dupes = 0;
+
+        for (int j = index + 1; j < keys.length; j++) {
+            if (keys[j] == null)
+                break; // keys.length doesn't shrink when removing, so re-test
+
+            if (isDuplicate(keys[index], keys[j], preserve)) {
+                dupes++;
+                remove(j);
+                j--;
             }
         }
         return dupes;
     }
 
+    private boolean isDuplicate(String key1, String key2, boolean preserve) {
+        return preserve ? key1.equals(key2) : key1.equalsIgnoreCase(key2);
+    }
+
     private static class Dataset extends AbstractMap<String, String> {
         private final Attributes attributes;
 
diff --git a/src/main/java/org/jsoup/nodes/Range.java b/src/main/java/org/jsoup/nodes/Range.java
index ccc1db5f51..d661470341 100644
--- a/src/main/java/org/jsoup/nodes/Range.java
+++ b/src/main/java/org/jsoup/nodes/Range.java
@@ -109,7 +109,7 @@ public boolean equals(Object o) {
     @Override
     public int hashCode() {
         int result = start.hashCode();
-        result = 31 * result + end.hashCode();
+        result = HashPrime * result + end.hashCode();
         return result;
     }
 
@@ -199,8 +199,8 @@ public boolean equals(Object o) {
         @Override
         public int hashCode() {
             int result = pos;
-            result = 31 * result + lineNumber;
-            result = 31 * result + columnNumber;
+            result = HashPrime * result + lineNumber;
+            result = HashPrime * result + columnNumber;
             return result;
         }
     }
@@ -246,7 +246,7 @@ public Range valueRange() {
 
         @Override public int hashCode() {
             int result = nameRange.hashCode();
-            result = 31 * result + valueRange.hashCode();
+            result = HashPrime * result + valueRange.hashCode();
             return result;
         }
     }