diff --git a/includes/sanitizers/class-amp-base-sanitizer.php b/includes/sanitizers/class-amp-base-sanitizer.php
index e371ce2b853..3a832acdf93 100644
--- a/includes/sanitizers/class-amp-base-sanitizer.php
+++ b/includes/sanitizers/class-amp-base-sanitizer.php
@@ -70,11 +70,11 @@ abstract class AMP_Base_Sanitizer {
 	protected $root_element;
 
 	/**
-	 * The plugin that is outputting markup, if any.
+	 * The plugin or theme that is outputting markup, if any.
 	 *
 	 * @var null|string
 	 */
-	public $current_plugin_output = null;
+	public $current_source = null;
 
 	/**
 	 * AMP_Base_Sanitizer constructor.
@@ -326,7 +326,7 @@ public function maybe_enforce_https_src( $src, $force_https = false ) {
 	public function remove_invalid_child( $child ) {
 		$child->parentNode->removeChild( $child );
 		if ( isset( $this->args[ AMP_Validation_Utils::CALLBACK_KEY ] ) ) {
-			call_user_func( $this->args[ AMP_Validation_Utils::CALLBACK_KEY ], $child, $this->current_plugin_output );
+			call_user_func( $this->args[ AMP_Validation_Utils::CALLBACK_KEY ], $child, $this->current_source );
 		}
 	}
 
@@ -349,7 +349,7 @@ public function remove_invalid_attribute( $element, $attribute ) {
 			}
 			if ( $attribute ) {
 				$element->removeAttributeNode( $attribute );
-				call_user_func( $this->args[ AMP_Validation_Utils::CALLBACK_KEY ], $attribute, $this->current_plugin_output );
+				call_user_func( $this->args[ AMP_Validation_Utils::CALLBACK_KEY ], $attribute, $this->current_source );
 			}
 		} elseif ( is_string( $attribute ) ) {
 			$element->removeAttribute( $attribute );
@@ -371,9 +371,9 @@ public function capture_current_source( $node ) {
 		if ( ! isset( $matches[1], $matches[2] ) ) {
 			return;
 		} elseif ( 'after' === $matches[1] ) {
-			$this->current_plugin_output = $matches[2];
+			$this->current_source = $matches[2];
 		} elseif ( 'before' === $matches[1] ) {
-			$this->current_plugin_output = null;
+			$this->current_source = null;
 		}
 	}
 
diff --git a/tests/test-class-amp-base-sanitizer.php b/tests/test-class-amp-base-sanitizer.php
index 4048481abfe..2a58f321b04 100644
--- a/tests/test-class-amp-base-sanitizer.php
+++ b/tests/test-class-amp-base-sanitizer.php
@@ -305,12 +305,12 @@ public function test_capture_current_source() {
 		$closing_comment = 'after:amp';
 		$node            = $dom->createComment( $closing_comment );
 		$sanitizer       = new AMP_Tag_And_Attribute_Sanitizer( $dom );
-		$this->assertEquals( null, $sanitizer->current_plugin_output );
+		$this->assertEquals( null, $sanitizer->current_source );
 		$sanitizer->capture_current_source( $node );
-		$this->assertEquals( 'amp', $sanitizer->current_plugin_output );
+		$this->assertEquals( 'amp', $sanitizer->current_source );
 		$opening_comment = $dom->createComment( 'before:amp' );
 		$sanitizer->capture_current_source( $opening_comment );
-		$this->assertEquals( null, $sanitizer->current_plugin_output );
+		$this->assertEquals( null, $sanitizer->current_source );
 	}
 
 }
diff --git a/tests/test-tag-and-attribute-sanitizer.php b/tests/test-tag-and-attribute-sanitizer.php
index 169974076d8..4df00d4266f 100644
--- a/tests/test-tag-and-attribute-sanitizer.php
+++ b/tests/test-tag-and-attribute-sanitizer.php
@@ -864,10 +864,10 @@ public function test_capture_current_source() {
 		$node           = $dom->createComment( $comment_after );
 		$sanitizer      = new AMP_Tag_And_Attribute_Sanitizer( $dom );
 		$sanitizer->capture_current_source( $node );
-		$this->assertEquals( 'amp', $sanitizer->current_plugin_output );
+		$this->assertEquals( 'amp', $sanitizer->current_source );
 		$closing_comment = $dom->createComment( $comment_before );
 		$sanitizer->capture_current_source( $closing_comment );
-		$this->assertEquals( null, $sanitizer->current_plugin_output );
+		$this->assertEquals( null, $sanitizer->current_source );
 	}
 
 }