diff --git a/core/fpdfapi/page/cpdf_pageobjectholder.cpp b/core/fpdfapi/page/cpdf_pageobjectholder.cpp
index 5bf627a..3c998d2 100644
--- a/core/fpdfapi/page/cpdf_pageobjectholder.cpp
+++ b/core/fpdfapi/page/cpdf_pageobjectholder.cpp
@@ -83,9 +83,6 @@
   if (pGroup->GetIntegerFor("I")) {
     m_iTransparency |= PDFTRANS_ISOLATED;
   }
-  if (pGroup->GetIntegerFor("K")) {
-    m_iTransparency |= PDFTRANS_KNOCKOUT;
-  }
 }
 
 size_t CPDF_PageObjectHolder::GetPageObjectCount() const {
diff --git a/core/fpdfapi/page/cpdf_pageobjectholder.h b/core/fpdfapi/page/cpdf_pageobjectholder.h
index b26fc0d..47c02fc 100644
--- a/core/fpdfapi/page/cpdf_pageobjectholder.h
+++ b/core/fpdfapi/page/cpdf_pageobjectholder.h
@@ -25,7 +25,6 @@
 
 #define PDFTRANS_GROUP 0x0100
 #define PDFTRANS_ISOLATED 0x0200
-#define PDFTRANS_KNOCKOUT 0x0400
 
 // These structs are used to keep track of resources that have already been
 // generated in the page object holder.