diff --git a/core/fpdfapi/page/cpdf_transparency.cpp b/core/fpdfapi/page/cpdf_transparency.cpp
index f9be541..b5498ec 100644
--- a/core/fpdfapi/page/cpdf_transparency.cpp
+++ b/core/fpdfapi/page/cpdf_transparency.cpp
@@ -7,3 +7,5 @@
 CPDF_Transparency::CPDF_Transparency() = default;
 
 CPDF_Transparency::CPDF_Transparency(const CPDF_Transparency& other) = default;
+CPDF_Transparency& CPDF_Transparency::operator=(
+    const CPDF_Transparency& other) = default;
diff --git a/core/fpdfapi/page/cpdf_transparency.h b/core/fpdfapi/page/cpdf_transparency.h
index 6d4972d..a01347b 100644
--- a/core/fpdfapi/page/cpdf_transparency.h
+++ b/core/fpdfapi/page/cpdf_transparency.h
@@ -10,6 +10,7 @@
   CPDF_Transparency();
 
   CPDF_Transparency(const CPDF_Transparency& other);
+  CPDF_Transparency& operator=(const CPDF_Transparency& other);
 
   bool IsGroup() const { return m_bGroup; }
   bool IsIsolated() const { return m_bIsolated; }
diff --git a/core/fpdfapi/render/cpdf_renderoptions.cpp b/core/fpdfapi/render/cpdf_renderoptions.cpp
index 80937de..805b91f 100644
--- a/core/fpdfapi/render/cpdf_renderoptions.cpp
+++ b/core/fpdfapi/render/cpdf_renderoptions.cpp
@@ -17,6 +17,9 @@
 CPDF_RenderOptions::Options::Options(const CPDF_RenderOptions::Options& rhs) =
     default;
 
+CPDF_RenderOptions::Options& CPDF_RenderOptions::Options::operator=(
+    const CPDF_RenderOptions::Options& rhs) = default;
+
 CPDF_RenderOptions::CPDF_RenderOptions() {
   // TODO(thestig): Make constexpr to initialize |m_Options| once C++14 is
   // available.
diff --git a/core/fpdfapi/render/cpdf_renderoptions.h b/core/fpdfapi/render/cpdf_renderoptions.h
index 2a383a5..b495a52 100644
--- a/core/fpdfapi/render/cpdf_renderoptions.h
+++ b/core/fpdfapi/render/cpdf_renderoptions.h
@@ -22,6 +22,7 @@
   struct Options {
     Options();
     Options(const Options& rhs);
+    Options& operator=(const Options& rhs);
 
     bool bClearType = false;
     bool bNoNativeText = false;