diff --git a/src/main/java/org/apache/commons/csv/CSVParser.java b/src/main/java/org/apache/commons/csv/CSVParser.java
index 471a43c1..98b797ca 100644
--- a/src/main/java/org/apache/commons/csv/CSVParser.java
+++ b/src/main/java/org/apache/commons/csv/CSVParser.java
@@ -504,44 +504,56 @@ public final class CSVParser implements Iterable<CSVRecord>, Closeable {
                 headerRecord = formatHeader;
             }
 
-            // build the name to index mappings
-            if (headerRecord != null) {
-                // Track an occurrence of a null, empty or blank header.
-                boolean observedMissing = false;
-                for (int i = 0; i < headerRecord.length; i++) {
-                    final String header = headerRecord[i];
-                    final boolean blankHeader = CSVFormat.isBlank(header);
-                    if (blankHeader && !format.getAllowMissingColumnNames()) {
-                        throw new IllegalArgumentException(
-                            "A header name is missing in " + Arrays.toString(headerRecord));
-                    }
-
-                    final boolean containsHeader = blankHeader ? observedMissing : hdrMap.containsKey(header);
-                    final DuplicateHeaderMode headerMode = format.getDuplicateHeaderMode();
-                    final boolean duplicatesAllowed = headerMode == DuplicateHeaderMode.ALLOW_ALL;
-                    final boolean emptyDuplicatesAllowed = headerMode == DuplicateHeaderMode.ALLOW_EMPTY;
-
-                    if (containsHeader && !duplicatesAllowed && !(blankHeader && emptyDuplicatesAllowed)) {
-                        throw new IllegalArgumentException(
-                            String.format(
-                                "The header contains a duplicate name: \"%s\" in %s. If this is valid then use CSVFormat.Builder.setDuplicateHeaderMode().",
-                                header, Arrays.toString(headerRecord)));
-                    }
-                    observedMissing |= blankHeader;
-                    if (header != null) {
-                        hdrMap.put(header, Integer.valueOf(i)); // N.B. Explicit (un)boxing is intentional
-                        if (headerNames == null) {
-                            headerNames = new ArrayList<>(headerRecord.length);
-                        }
-                        headerNames.add(header);
-                    }
-                }
-            }
+            headerNames = getHeaderNames(headerRecord, hdrMap);
         }
         // Make header names Collection immutable
         return new Headers(hdrMap, headerNames == null ? Collections.emptyList() : Collections.unmodifiableList(headerNames));
     }
 
+    /**
+     *  Build the name to index mappings
+     *
+     * @param headerRecord the record as an array of values, or {@code null} if the end of the stream has been reached
+     * @param headerMap the header column positions (0-based)
+     * @return header names in column order, or {@code null} if {@code headerRecord} is {@code null}.
+     */
+    private List<String> getHeaderNames(final String[] headerRecord, final Map<String, Integer> headerMap) {
+        List<String> headerNames = null;
+        if (headerRecord != null) {
+            // Track an occurrence of a null, empty or blank header.
+            boolean observedMissing = false;
+            for (int i = 0; i < headerRecord.length; i++) {
+                final String header = headerRecord[i];
+                final boolean blankHeader = CSVFormat.isBlank(header);
+                if (blankHeader && !format.getAllowMissingColumnNames()) {
+                    throw new IllegalArgumentException(
+                        "A header name is missing in " + Arrays.toString(headerRecord));
+                }
+
+                final boolean containsHeader = blankHeader ? observedMissing : headerMap.containsKey(header);
+                final DuplicateHeaderMode headerMode = format.getDuplicateHeaderMode();
+                final boolean duplicatesAllowed = headerMode == DuplicateHeaderMode.ALLOW_ALL;
+                final boolean emptyDuplicatesAllowed = headerMode == DuplicateHeaderMode.ALLOW_EMPTY;
+
+                if (containsHeader && !duplicatesAllowed && !(blankHeader && emptyDuplicatesAllowed)) {
+                    throw new IllegalArgumentException(
+                        String.format(
+                            "The header contains a duplicate name: \"%s\" in %s. If this is valid then use CSVFormat.Builder.setDuplicateHeaderMode().",
+                            header, Arrays.toString(headerRecord)));
+                }
+                observedMissing |= blankHeader;
+                if (header != null) {
+                    headerMap.put(header, Integer.valueOf(i)); // N.B. Explicit (un)boxing is intentional
+                    if (headerNames == null) {
+                        headerNames = new ArrayList<>(headerRecord.length);
+                    }
+                    headerNames.add(header);
+                }
+            }
+        }
+        return headerNames;
+    }
+
     /**
      * Gets the current line number in the input stream.
      *