diff --git a/core/fpdfapi/font/cpdf_font.h b/core/fpdfapi/font/cpdf_font.h
index db776fd..d504bfe 100644
--- a/core/fpdfapi/font/cpdf_font.h
+++ b/core/fpdfapi/font/cpdf_font.h
@@ -57,7 +57,7 @@
         CPDF_Stream* pFormStream) = 0;
   };
 
-  static const uint32_t kInvalidCharCode = static_cast<uint32_t>(-1);
+  static constexpr uint32_t kInvalidCharCode = static_cast<uint32_t>(-1);
 
   // |pFactory| only required for Type3 fonts.
   static RetainPtr<CPDF_Font> Create(CPDF_Document* pDoc,
diff --git a/core/fpdfapi/page/cpdf_meshstream.h b/core/fpdfapi/page/cpdf_meshstream.h
index 939b192..5f93e0d 100644
--- a/core/fpdfapi/page/cpdf_meshstream.h
+++ b/core/fpdfapi/page/cpdf_meshstream.h
@@ -64,7 +64,7 @@
   uint32_t Components() const { return m_nComponents; }
 
  private:
-  static const uint32_t kMaxComponents = 8;
+  static constexpr uint32_t kMaxComponents = 8;
 
   const ShadingType m_type;
   const std::vector<std::unique_ptr<CPDF_Function>>& m_funcs;
diff --git a/core/fpdfapi/page/cpdf_psengine.h b/core/fpdfapi/page/cpdf_psengine.h
index 3db8db7..faf8d94 100644
--- a/core/fpdfapi/page/cpdf_psengine.h
+++ b/core/fpdfapi/page/cpdf_psengine.h
@@ -98,7 +98,7 @@
   }
 
  private:
-  static const int kMaxDepth = 128;
+  static constexpr int kMaxDepth = 128;
 
   void AddOperator(ByteStringView word);
 
diff --git a/core/fpdfapi/page/cpdf_streamcontentparser.h b/core/fpdfapi/page/cpdf_streamcontentparser.h
index a270320..f9b4da2 100644
--- a/core/fpdfapi/page/cpdf_streamcontentparser.h
+++ b/core/fpdfapi/page/cpdf_streamcontentparser.h
@@ -76,7 +76,7 @@
     RetainPtr<CPDF_Object> m_pObject;
   };
 
-  static const int kParamBufSize = 16;
+  static constexpr int kParamBufSize = 16;
 
   using OpCodes = std::map<uint32_t, void (CPDF_StreamContentParser::*)()>;
   static OpCodes InitializeOpCodes();
diff --git a/core/fpdfapi/page/cpdf_streamparser.h b/core/fpdfapi/page/cpdf_streamparser.h
index 81a1246..a5ffc77 100644
--- a/core/fpdfapi/page/cpdf_streamparser.h
+++ b/core/fpdfapi/page/cpdf_streamparser.h
@@ -44,7 +44,7 @@
 
  private:
   friend class cpdf_streamparser_ReadHexString_Test;
-  static const uint32_t kMaxWordLength = 255;
+  static constexpr uint32_t kMaxWordLength = 255;
 
   void GetNextWord(bool& bIsNumber);
   ByteString ReadString();
diff --git a/core/fpdfapi/parser/cpdf_data_avail.h b/core/fpdfapi/parser/cpdf_data_avail.h
index 8552980..f9cd981 100644
--- a/core/fpdfapi/parser/cpdf_data_avail.h
+++ b/core/fpdfapi/parser/cpdf_data_avail.h
@@ -125,7 +125,7 @@
     std::vector<std::unique_ptr<PageNode>> m_ChildNodes;
   };
 
-  static const int kMaxPageRecursionDepth = 1024;
+  static constexpr int kMaxPageRecursionDepth = 1024;
 
   bool CheckDocStatus();
   bool CheckHeader();
diff --git a/core/fpdfapi/parser/cpdf_document.h b/core/fpdfapi/parser/cpdf_document.h
index 3506e59..56168e9 100644
--- a/core/fpdfapi/parser/cpdf_document.h
+++ b/core/fpdfapi/parser/cpdf_document.h
@@ -74,7 +74,7 @@
     UnownedPtr<CPDF_Document> m_pDoc;
   };
 
-  static const int kPageMaxNum = 0xFFFFF;
+  static constexpr int kPageMaxNum = 0xFFFFF;
 
   static bool IsValidPageObject(const CPDF_Object* obj);
 
diff --git a/core/fpdfapi/parser/cpdf_object.h b/core/fpdfapi/parser/cpdf_object.h
index 77810ca..93dbbaa 100644
--- a/core/fpdfapi/parser/cpdf_object.h
+++ b/core/fpdfapi/parser/cpdf_object.h
@@ -29,7 +29,7 @@
 
 class CPDF_Object : public Retainable {
  public:
-  static const uint32_t kInvalidObjNum = static_cast<uint32_t>(-1);
+  static constexpr uint32_t kInvalidObjNum = static_cast<uint32_t>(-1);
   enum Type {
     kBoolean = 1,
     kNumber,
@@ -125,10 +125,10 @@
 
 template <typename T>
 struct CanInternStrings {
-  static const bool value = std::is_same<T, CPDF_Array>::value ||
-                            std::is_same<T, CPDF_Dictionary>::value ||
-                            std::is_same<T, CPDF_Name>::value ||
-                            std::is_same<T, CPDF_String>::value;
+  static constexpr bool value = std::is_same<T, CPDF_Array>::value ||
+                                std::is_same<T, CPDF_Dictionary>::value ||
+                                std::is_same<T, CPDF_Name>::value ||
+                                std::is_same<T, CPDF_String>::value;
 };
 
 #endif  // CORE_FPDFAPI_PARSER_CPDF_OBJECT_H_
diff --git a/core/fpdfapi/parser/cpdf_parser.h b/core/fpdfapi/parser/cpdf_parser.h
index aa86701..c9b590e 100644
--- a/core/fpdfapi/parser/cpdf_parser.h
+++ b/core/fpdfapi/parser/cpdf_parser.h
@@ -53,7 +53,7 @@
   // are non-consecutive.
   static constexpr uint32_t kMaxObjectNumber = 4 * 1024 * 1024;
 
-  static const size_t kInvalidPos = std::numeric_limits<size_t>::max();
+  static constexpr size_t kInvalidPos = std::numeric_limits<size_t>::max();
 
   explicit CPDF_Parser(ParsedObjectsHolder* holder);
   CPDF_Parser();
diff --git a/core/fpdfapi/parser/cpdf_stream.h b/core/fpdfapi/parser/cpdf_stream.h
index d29f655..3dba365 100644
--- a/core/fpdfapi/parser/cpdf_stream.h
+++ b/core/fpdfapi/parser/cpdf_stream.h
@@ -17,7 +17,7 @@
 
 class CPDF_Stream final : public CPDF_Object {
  public:
-  static const int kFileBufSize = 512;
+  static constexpr int kFileBufSize = 512;
 
   template <typename T, typename... Args>
   friend RetainPtr<T> pdfium::MakeRetain(Args&&... args);
diff --git a/core/fpdfapi/parser/cpdf_syntax_parser.h b/core/fpdfapi/parser/cpdf_syntax_parser.h
index d0b8a31..bdcfa44 100644
--- a/core/fpdfapi/parser/cpdf_syntax_parser.h
+++ b/core/fpdfapi/parser/cpdf_syntax_parser.h
@@ -79,7 +79,7 @@
   friend class CPDF_DataAvail;
   friend class cpdf_syntax_parser_ReadHexString_Test;
 
-  static const int kParserMaxRecursionDepth = 64;
+  static constexpr int kParserMaxRecursionDepth = 64;
   static int s_CurrentRecursionDepth;
 
   bool ReadBlockAt(FX_FILESIZE read_pos);
diff --git a/core/fpdfapi/render/cpdf_progressiverenderer.h b/core/fpdfapi/render/cpdf_progressiverenderer.h
index fd399f9..403a577 100644
--- a/core/fpdfapi/render/cpdf_progressiverenderer.h
+++ b/core/fpdfapi/render/cpdf_progressiverenderer.h
@@ -42,7 +42,7 @@
 
  private:
   // Maximum page objects to render before checking for pause.
-  static const int kStepLimit = 100;
+  static constexpr int kStepLimit = 100;
 
   Status m_Status = kReady;
   UnownedPtr<CPDF_RenderContext> const m_pContext;
diff --git a/core/fxcodec/jpeg/jpegmodule.cpp b/core/fxcodec/jpeg/jpegmodule.cpp
index 72925f1..c9b2e79 100644
--- a/core/fxcodec/jpeg/jpegmodule.cpp
+++ b/core/fxcodec/jpeg/jpegmodule.cpp
@@ -264,7 +264,7 @@
   // For a given invalid height byte offset in
   // |kKnownBadHeaderWithInvalidHeightByteOffsetStarts|, the SOFn marker should
   // be this many bytes before that.
-  static const size_t kSofMarkerByteOffset = 5;
+  static constexpr size_t kSofMarkerByteOffset = 5;
 
   uint32_t m_nDefaultScaleDenom = 1;
 };
diff --git a/core/fxge/cfx_font.h b/core/fxge/cfx_font.h
index ead60f7..9658ac2 100644
--- a/core/fxge/cfx_font.h
+++ b/core/fxge/cfx_font.h
@@ -107,9 +107,9 @@
   void SetPlatformFont(void* font) { m_pPlatformFont = font; }
 #endif
 
-  static const size_t kAngleSkewArraySize = 30;
+  static constexpr size_t kAngleSkewArraySize = 30;
   static const char s_AngleSkew[kAngleSkewArraySize];
-  static const size_t kWeightPowArraySize = 100;
+  static constexpr size_t kWeightPowArraySize = 100;
   static const uint8_t s_WeightPow[kWeightPowArraySize];
   static const uint8_t s_WeightPow_11[kWeightPowArraySize];
   static const uint8_t s_WeightPow_SHIFTJIS[kWeightPowArraySize];
diff --git a/core/fxge/cfx_fontmapper.h b/core/fxge/cfx_fontmapper.h
index c21c6cb..d063adf 100644
--- a/core/fxge/cfx_fontmapper.h
+++ b/core/fxge/cfx_fontmapper.h
@@ -76,8 +76,8 @@
   std::vector<std::pair<ByteString, ByteString>> m_LocalizedTTFonts;
 
  private:
-  static const size_t MM_FACE_COUNT = 2;
-  static const size_t FOXIT_FACE_COUNT = 14;
+  static constexpr size_t MM_FACE_COUNT = 2;
+  static constexpr size_t FOXIT_FACE_COUNT = 14;
 
   uint32_t GetChecksumFromTT(void* hFont);
   ByteString GetPSNameFromTT(void* hFont);