diff --git a/core/fpdfapi/page/cpdf_dib.cpp b/core/fpdfapi/page/cpdf_dib.cpp
index 7dc2324..d1ab8c8 100644
--- a/core/fpdfapi/page/cpdf_dib.cpp
+++ b/core/fpdfapi/page/cpdf_dib.cpp
@@ -251,7 +251,7 @@
     const CPDF_Stream* pStream,
     bool bHasMask,
     const CPDF_Dictionary* pFormResources,
-    CPDF_Dictionary* pPageResources,
+    const CPDF_Dictionary* pPageResources,
     bool bStdCS,
     uint32_t GroupFamily,
     bool bLoadMask) {
diff --git a/core/fpdfapi/page/cpdf_dib.h b/core/fpdfapi/page/cpdf_dib.h
index 66decf3..94db0e7 100644
--- a/core/fpdfapi/page/cpdf_dib.h
+++ b/core/fpdfapi/page/cpdf_dib.h
@@ -63,7 +63,7 @@
                              const CPDF_Stream* pStream,
                              bool bHasMask,
                              const CPDF_Dictionary* pFormResources,
-                             CPDF_Dictionary* pPageResources,
+                             const CPDF_Dictionary* pPageResources,
                              bool bStdCS,
                              uint32_t GroupFamily,
                              bool bLoadMask);
diff --git a/core/fpdfapi/page/cpdf_image.cpp b/core/fpdfapi/page/cpdf_image.cpp
index f87a157..0262bce 100644
--- a/core/fpdfapi/page/cpdf_image.cpp
+++ b/core/fpdfapi/page/cpdf_image.cpp
@@ -350,7 +350,7 @@
 }
 
 bool CPDF_Image::StartLoadDIBBase(const CPDF_Dictionary* pFormResource,
-                                  CPDF_Dictionary* pPageResource,
+                                  const CPDF_Dictionary* pPageResource,
                                   bool bStdCS,
                                   uint32_t GroupFamily,
                                   bool bLoadMask) {
diff --git a/core/fpdfapi/page/cpdf_image.h b/core/fpdfapi/page/cpdf_image.h
index d5d8c0b..11a582d 100644
--- a/core/fpdfapi/page/cpdf_image.h
+++ b/core/fpdfapi/page/cpdf_image.h
@@ -54,7 +54,7 @@
 
   // Returns whether to Continue() or not.
   bool StartLoadDIBBase(const CPDF_Dictionary* pFormResource,
-                        CPDF_Dictionary* pPageResource,
+                        const CPDF_Dictionary* pPageResource,
                         bool bStdCS,
                         uint32_t GroupFamily,
                         bool bLoadMask);
diff --git a/core/fpdfapi/render/cpdf_imagecacheentry.cpp b/core/fpdfapi/render/cpdf_imagecacheentry.cpp
index fa25896..9513a81 100644
--- a/core/fpdfapi/render/cpdf_imagecacheentry.cpp
+++ b/core/fpdfapi/render/cpdf_imagecacheentry.cpp
@@ -54,7 +54,7 @@
 }
 
 CPDF_DIB::LoadState CPDF_ImageCacheEntry::StartGetCachedBitmap(
-    CPDF_Dictionary* pPageResources,
+    const CPDF_Dictionary* pPageResources,
     const CPDF_RenderStatus* pRenderStatus,
     bool bStdCS) {
   if (m_pCachedBitmap) {
diff --git a/core/fpdfapi/render/cpdf_imagecacheentry.h b/core/fpdfapi/render/cpdf_imagecacheentry.h
index 46e3f89..c48554e 100644
--- a/core/fpdfapi/render/cpdf_imagecacheentry.h
+++ b/core/fpdfapi/render/cpdf_imagecacheentry.h
@@ -30,7 +30,7 @@
   CPDF_Image* GetImage() const { return m_pImage.Get(); }
 
   CPDF_DIB::LoadState StartGetCachedBitmap(
-      CPDF_Dictionary* pPageResources,
+      const CPDF_Dictionary* pPageResources,
       const CPDF_RenderStatus* pRenderStatus,
       bool bStdCS);
 
diff --git a/core/fpdfapi/render/cpdf_renderstatus.h b/core/fpdfapi/render/cpdf_renderstatus.h
index 76eb71c..f5ed945 100644
--- a/core/fpdfapi/render/cpdf_renderstatus.h
+++ b/core/fpdfapi/render/cpdf_renderstatus.h
@@ -86,7 +86,9 @@
   const CPDF_Dictionary* GetFormResource() const {
     return m_pFormResource.Get();
   }
-  CPDF_Dictionary* GetPageResource() const { return m_pPageResource.Get(); }
+  const CPDF_Dictionary* GetPageResource() const {
+    return m_pPageResource.Get();
+  }
   CFX_RenderDevice* GetRenderDevice() const { return m_pDevice; }
   const CPDF_RenderOptions& GetRenderOptions() const { return m_Options; }