4 files changed, 4 insertions, 4 deletions
diff --git a/core/fpdfapi/fpdf_page/cpdf_colorstate.h b/core/fpdfapi/fpdf_page/cpdf_colorstate.h
index d928dbdb2e..a4077d965f 100644
--- a/core/fpdfapi/fpdf_page/cpdf_colorstate.h
+++ b/core/fpdfapi/fpdf_page/cpdf_colorstate.h
@@ -51,7 +51,7 @@ class CPDF_ColorState {
   // TODO(tsepez): Stop leaking ColorStateData outside this class.
   const CPDF_ColorStateData* GetObject() const { return m_Ref.GetObject(); }
 
-  operator bool() const { return !!m_Ref; }
+  explicit operator bool() const { return !!m_Ref; }
 
  private:
   void SetColor(CPDF_Color& color,
diff --git a/core/fpdfapi/fpdf_page/cpdf_contentmark.h b/core/fpdfapi/fpdf_page/cpdf_contentmark.h
index 2941c61ba9..25da5889df 100644
--- a/core/fpdfapi/fpdf_page/cpdf_contentmark.h
+++ b/core/fpdfapi/fpdf_page/cpdf_contentmark.h
@@ -30,7 +30,7 @@ class CPDF_ContentMark {
                FX_BOOL bDirect);
   void DeleteLastMark();
 
-  operator bool() const { return !!m_Ref; }
+  explicit operator bool() const { return !!m_Ref; }
 
  private:
   CFX_CountRef<CPDF_ContentMarkData> m_Ref;
diff --git a/core/fpdfapi/fpdf_page/include/cpdf_generalstate.h b/core/fpdfapi/fpdf_page/include/cpdf_generalstate.h
index f07e411973..1cd2d815c8 100644
--- a/core/fpdfapi/fpdf_page/include/cpdf_generalstate.h
+++ b/core/fpdfapi/fpdf_page/include/cpdf_generalstate.h
@@ -21,7 +21,7 @@ class CPDF_GeneralState {
   ~CPDF_GeneralState();
 
   void Emplace() { m_Ref.Emplace(); }
-  operator bool() const { return !!m_Ref; }
+  explicit operator bool() const { return !!m_Ref; }
 
   void SetRenderIntent(const CFX_ByteString& ri);
 
diff --git a/core/fpdfapi/fpdf_page/include/cpdf_path.h b/core/fpdfapi/fpdf_page/include/cpdf_path.h
index a9b0a7fac0..ae98531214 100644
--- a/core/fpdfapi/fpdf_page/include/cpdf_path.h
+++ b/core/fpdfapi/fpdf_page/include/cpdf_path.h
@@ -20,7 +20,7 @@ class CPDF_Path {
   ~CPDF_Path();
 
   void Emplace() { m_Ref.Emplace(); }
-  operator bool() const { return !!m_Ref; }
+  explicit operator bool() const { return !!m_Ref; }
 
   int GetPointCount() const;
   void SetPointCount(int count);