diff --git a/app/PriorPrice/HistoryStorage.php b/app/PriorPrice/HistoryStorage.php
index 7756641..fb7d8c2 100644
--- a/app/PriorPrice/HistoryStorage.php
+++ b/app/PriorPrice/HistoryStorage.php
@@ -32,11 +32,13 @@ public function get_minimal( int $product_id, int $days = 30 ) : float {
 
 		$history = $this->get_history( $product_id );
 
+		$this_ = $this;
+
 		// Get only $days last items.
 		$the_last = array_filter(
 			$history,
-			static function( $timestamp ) use ( $days ) {
-				return $timestamp >= ( time() - ( $days * DAY_IN_SECONDS ) );
+			static function( $timestamp ) use ( $days, $this_ ) {
+				return $timestamp >= ( $this_->get_time_with_offset() - ( $days * DAY_IN_SECONDS ) );
 			},
 			ARRAY_FILTER_USE_KEY
 		);
@@ -106,7 +108,7 @@ public function add_price( int $product_id, float $price, bool $on_change_only )
 			return 0;
 		}
 
-		$history[ time() + ( get_option( 'gmt_offset' ) * HOUR_IN_SECONDS ) ] = $price;
+		$history[ $this->get_time_with_offset() ] = $price;
 
 		return $this->save_history( $product_id, $history );
 	}
@@ -161,7 +163,7 @@ public function get_history( int $product_id ) : array {
 	private function fill_empty_history( int $product_id, array $history ) : array {
 
 		if ( empty( $history ) ) {
-			$history[ time() ] = get_post_meta( $product_id, '_price', true );
+			$history[ $this->get_time_with_offset() ] = get_post_meta( $product_id, '_price', true );
 
 			$this->save_history( $product_id, $history );
 		}
@@ -206,4 +208,16 @@ static function( $carry, $item ) {
 			}
 		);
 	}
+
+	/**
+	 * Get time with offset.
+	 *
+	 * @since 1.6.1
+	 *
+	 * @return int
+	 */
+	private function get_time_with_offset() : int {
+
+		return time() + ( (int) get_option( 'gmt_offset' ) * HOUR_IN_SECONDS );
+	}
 }
diff --git a/tests/phpunit/HistoryStorageTest.php b/tests/phpunit/HistoryStorageTest.php
index 8c248f4..b2679d0 100644
--- a/tests/phpunit/HistoryStorageTest.php
+++ b/tests/phpunit/HistoryStorageTest.php
@@ -33,6 +33,11 @@ public function test_get_minimal( $history, $expected_minimal ) {
 			'return' => $history
 		] );
 
+		\WP_Mock::userFunction( 'get_option', [
+			'args' => [ 'gmt_offset' ],
+			'return' => 0
+		] );
+
 
 		$minimal = $subject->get_minimal( $product_id, 30 );