diff --git a/includes/class-wc-datetime.php b/includes/class-wc-datetime.php
index fe7873d78f9..985efff2d78 100644
--- a/includes/class-wc-datetime.php
+++ b/includes/class-wc-datetime.php
@@ -5,7 +5,8 @@ if ( ! defined( 'ABSPATH' ) ) {
 }
 
 /**
- * WC Wrapper for PHP DateTime.
+ * WC Wrapper for PHP DateTime which adds support for gmt/utc offset when a
+ * timezone is absent.
  *
  * @class    WC_DateTime
  * @since    3.0.0
@@ -16,13 +17,15 @@ if ( ! defined( 'ABSPATH' ) ) {
 class WC_DateTime extends DateTime {
 
 	/**
-	 * UTC Offset if needed.
+	 * UTC Offset, if needed. Only used when a timezone is not set. When
+	 * timezones are used this will equal 0.
+	 *
 	 * @var integer
 	 */
 	protected $utc_offset = 0;
 
 	/**
-	 * Output an ISO 8601 date string in local timezone.
+	 * Output an ISO 8601 date string in local (WordPress) timezone.
 	 *
 	 * @since  3.0.0
 	 * @return string
@@ -32,7 +35,7 @@ class WC_DateTime extends DateTime {
 	}
 
 	/**
-	 * Set UTC offset.
+	 * Set UTC offset - this is a fixed offset instead of a timezone.
 	 *
 	 * @param int $offset
 	 */
@@ -41,7 +44,7 @@ class WC_DateTime extends DateTime {
 	}
 
 	/**
-	 * getOffset.
+	 * Get UTC offset if set, or default to the DateTime object's offset.
 	 */
 	public function getOffset() {
 		if ( $this->utc_offset ) {
@@ -64,7 +67,7 @@ class WC_DateTime extends DateTime {
 	}
 
 	/**
-	 * Missing in PHP 5.2.
+	 * Missing in PHP 5.2 so just here so it can be supported consistently.
 	 *
 	 * @since  3.0.0
 	 * @return int
diff --git a/includes/import/class-wc-product-csv-importer.php b/includes/import/class-wc-product-csv-importer.php
index 19b52b692de..8ac995e10c0 100644
--- a/includes/import/class-wc-product-csv-importer.php
+++ b/includes/import/class-wc-product-csv-importer.php
@@ -186,10 +186,9 @@ class WC_Product_CSV_Importer extends WC_Product_Importer {
 	 * for rows following this one.
 	 *
 	 * @param  stirng $field
-	 * @param  array $raw_data
 	 * @return int
 	 */
-	public function parse_id_field( $field, $raw_data = array() ) {
+	public function parse_id_field( $field ) {
 		global $wpdb;
 
 		$id = absint( $field );
@@ -208,7 +207,7 @@ class WC_Product_CSV_Importer extends WC_Product_Importer {
 		// Not updating? Make sure we have a new placeholder for this ID.
 		if ( ! $this->params['update_existing'] ) {
 			// If row has a SKU, make sure placeholder was not made already.
-			if ( isset( $raw_data['sku'] ) && $id = wc_get_product_id_by_sku( $raw_data['sku'] ) ) {
+			if ( isset( $this->raw_data['sku'] ) && $id = wc_get_product_id_by_sku( $this->raw_data['sku'] ) ) {
 				return $id;
 			}
 
@@ -218,8 +217,8 @@ class WC_Product_CSV_Importer extends WC_Product_Importer {
 			$product->add_meta_data( '_original_id', $id, true );
 
 			// If row has a SKU, make sure placeholder has it too.
-			if ( isset( $raw_data['sku'] ) ) {
-				$product->set_sku( $raw_data['sku'] );
+			if ( isset( $this->raw_data['sku'] ) ) {
+				$product->set_sku( $this->raw_data['sku'] );
 			}
 			$id = $product->save();
 		}
@@ -705,7 +704,7 @@ class WC_Product_CSV_Importer extends WC_Product_Importer {
 					$value = wp_check_invalid_utf8( $value, true );
 				}
 
-				$data[ $mapped_keys[ $id ] ] = call_user_func( $parse_functions[ $id ], $value, array_combine( $mapped_keys, $row ) );
+				$data[ $mapped_keys[ $id ] ] = call_user_func( $parse_functions[ $id ], $value );
 			}
 
 			$this->parsed_data[] = apply_filters( 'woocommerce_product_importer_parsed_data', $this->expand_data( $data ), $this );