diff --git a/fxjs/cjs_util.cpp b/fxjs/cjs_util.cpp
index 9d11c7a..81820fe 100644
--- a/fxjs/cjs_util.cpp
+++ b/fxjs/cjs_util.cpp
@@ -135,14 +135,14 @@
 
     WideString segment;
     switch (ParseDataType(&fmt)) {
-      case UTIL_INT:
+      case DataType::kInt:
         segment = WideString::Format(fmt.c_str(), pRuntime->ToInt32(params[i]));
         break;
-      case UTIL_DOUBLE:
+      case DataType::kDouble:
         segment =
             WideString::Format(fmt.c_str(), pRuntime->ToDouble(params[i]));
         break;
-      case UTIL_STRING:
+      case DataType::kString:
         segment = WideString::Format(fmt.c_str(),
                                      pRuntime->ToWideString(params[i]).c_str());
         break;
@@ -398,10 +398,10 @@
 }
 
 // static
-int CJS_Util::ParseDataType(WideString* sFormat) {
+CJS_Util::DataType CJS_Util::ParseDataType(WideString* sFormat) {
   enum State { BEFORE, FLAGS, WIDTH, PRECISION, SPECIFIER, AFTER };
 
-  int result = -1;
+  DataType result = DataType::kInvalid;
   State state = BEFORE;
   size_t precision_digits = 0;
   size_t i = 0;
@@ -422,7 +422,7 @@
         break;
       case WIDTH:
         if (c == L'*')
-          return -1;
+          return DataType::kInvalid;
         if (FXSYS_IsDecimalDigit(c)) {
           // Stay in same state.
         } else if (c == L'.') {
@@ -434,7 +434,7 @@
         break;
       case PRECISION:
         if (c == L'*')
-          return -1;
+          return DataType::kInvalid;
         if (FXSYS_IsDecimalDigit(c)) {
           // Stay in same state.
           ++precision_digits;
@@ -446,32 +446,32 @@
       case SPECIFIER:
         if (c == L'c' || c == L'C' || c == L'd' || c == L'i' || c == L'o' ||
             c == L'u' || c == L'x' || c == L'X') {
-          result = UTIL_INT;
+          result = DataType::kInt;
         } else if (c == L'e' || c == L'E' || c == L'f' || c == L'g' ||
                    c == L'G') {
-          result = UTIL_DOUBLE;
+          result = DataType::kDouble;
         } else if (c == L's' || c == L'S') {
           // Map s to S since we always deal internally with wchar_t strings.
           // TODO(tsepez): Probably 100% borked. %S is not a standard
           // conversion.
           sFormat->SetAt(i, L'S');
-          result = UTIL_STRING;
+          result = DataType::kString;
         } else {
-          return -1;
+          return DataType::kInvalid;
         }
         state = AFTER;
         break;
       case AFTER:
         if (c == L'%')
-          return -1;
+          return DataType::kInvalid;
         // Stay in same state until string exhausted.
         break;
     }
     ++i;
   }
   // See https://crbug.com/740166
-  if (result == UTIL_INT && precision_digits > 2)
-    return -1;
+  if (result == DataType::kInt && precision_digits > 2)
+    return DataType::kInvalid;
 
   return result;
 }
diff --git a/fxjs/cjs_util.h b/fxjs/cjs_util.h
index e565520..2ad4d27 100644
--- a/fxjs/cjs_util.h
+++ b/fxjs/cjs_util.h
@@ -13,13 +13,15 @@
 #include "fxjs/cjs_object.h"
 #include "fxjs/js_define.h"
 
-// Return values for ParseDataType() below.
-#define UTIL_INT 0
-#define UTIL_DOUBLE 1
-#define UTIL_STRING 2
-
 class CJS_Util final : public CJS_Object {
  public:
+  enum class DataType {
+    kInvalid = -1,
+    kInt = 0,
+    kDouble = 1,
+    kString = 2,
+  };
+
   static uint32_t GetObjDefnID();
   static void DefineJSObjects(CFXJS_Engine* pEngine);
 
@@ -33,7 +35,7 @@
   // byte-by-byte.
   //
   // Exposed for testing.
-  static int ParseDataType(WideString* sFormat);
+  static DataType ParseDataType(WideString* sFormat);
 
   // Exposed for testing.
   static WideString StringPrintx(const WideString& cFormat,
diff --git a/fxjs/cjs_util_unittest.cpp b/fxjs/cjs_util_unittest.cpp
index b4c07f7..77fa270 100644
--- a/fxjs/cjs_util_unittest.cpp
+++ b/fxjs/cjs_util_unittest.cpp
@@ -10,99 +10,99 @@
 TEST(CJS_Util, ParseDataType) {
   struct ParseDataTypeCase {
     const wchar_t* const input_string;
-    const int expected;
+    const CJS_Util::DataType expected;
   };
 
   // Commented out tests follow the spec but are not passing.
   const ParseDataTypeCase cases[] = {
       // Not conversions
-      {L"", -1},
-      {L"d", -1},
+      {L"", CJS_Util::DataType::kInvalid},
+      {L"d", CJS_Util::DataType::kInvalid},
 
       // Simple cases
-      {L"%d", UTIL_INT},
-      {L"%x", UTIL_INT},
-      {L"%f", UTIL_DOUBLE},
-      {L"%s", UTIL_STRING},
+      {L"%d", CJS_Util::DataType::kInt},
+      {L"%x", CJS_Util::DataType::kInt},
+      {L"%f", CJS_Util::DataType::kDouble},
+      {L"%s", CJS_Util::DataType::kString},
 
       // nDecSep Not implemented
-      // {L"%,0d", UTIL_INT},
-      // {L"%,1d", UTIL_INT},
-      // {L"%,2d", UTIL_INT},
-      // {L"%,3d", UTIL_INT},
+      // {L"%,0d", CJS_Util::DataType::kInt},
+      // {L"%,1d", CJS_Util::DataType::kInt},
+      // {L"%,2d", CJS_Util::DataType::kInt},
+      // {L"%,3d", CJS_Util::DataType::kInt},
       // {L"%,4d", -1},
       // {L"%,d", -1},
 
       // cFlags("+ 0#"") are only valid for numeric conversions.
-      {L"%+d", UTIL_INT},
-      {L"%+x", UTIL_INT},
-      {L"%+f", UTIL_DOUBLE},
+      {L"%+d", CJS_Util::DataType::kInt},
+      {L"%+x", CJS_Util::DataType::kInt},
+      {L"%+f", CJS_Util::DataType::kDouble},
       // {L"%+s", -1},
-      {L"% d", UTIL_INT},
-      {L"% x", UTIL_INT},
-      {L"% f", UTIL_DOUBLE},
+      {L"% d", CJS_Util::DataType::kInt},
+      {L"% x", CJS_Util::DataType::kInt},
+      {L"% f", CJS_Util::DataType::kDouble},
       // {L"% s", -1},
-      {L"%0d", UTIL_INT},
-      {L"%0x", UTIL_INT},
-      {L"%0f", UTIL_DOUBLE},
+      {L"%0d", CJS_Util::DataType::kInt},
+      {L"%0x", CJS_Util::DataType::kInt},
+      {L"%0f", CJS_Util::DataType::kDouble},
       // {L"%0s", -1},
-      {L"%#d", UTIL_INT},
-      {L"%#x", UTIL_INT},
-      {L"%#f", UTIL_DOUBLE},
+      {L"%#d", CJS_Util::DataType::kInt},
+      {L"%#x", CJS_Util::DataType::kInt},
+      {L"%#f", CJS_Util::DataType::kDouble},
       // {L"%#s", -1},
 
       // nWidth should work. for all conversions, can be combined with cFlags=0
       // for numbers.
-      {L"%5d", UTIL_INT},
-      {L"%05d", UTIL_INT},
-      {L"%5x", UTIL_INT},
-      {L"%05x", UTIL_INT},
-      {L"%5f", UTIL_DOUBLE},
-      {L"%05f", UTIL_DOUBLE},
-      {L"%5s", UTIL_STRING},
+      {L"%5d", CJS_Util::DataType::kInt},
+      {L"%05d", CJS_Util::DataType::kInt},
+      {L"%5x", CJS_Util::DataType::kInt},
+      {L"%05x", CJS_Util::DataType::kInt},
+      {L"%5f", CJS_Util::DataType::kDouble},
+      {L"%05f", CJS_Util::DataType::kDouble},
+      {L"%5s", CJS_Util::DataType::kString},
       // {L"%05s", -1},
 
       // nPrecision should only work for float
       // {L"%.5d", -1},
       // {L"%.5x", -1},
-      {L"%.5f", UTIL_DOUBLE},
+      {L"%.5f", CJS_Util::DataType::kDouble},
       // {L"%.5s", -1},
       // {L"%.14d", -1},
       // {L"%.14x", -1},
-      {L"%.14f", UTIL_DOUBLE},
+      {L"%.14f", CJS_Util::DataType::kDouble},
       // {L"%.14s", -1},
       // {L"%.f", -1},
 
       // See https://crbug.com/740166
       // nPrecision too large (> 260) causes crashes in Windows.
       // Avoid this by limiting to two digits
-      {L"%.1d", UTIL_INT},
-      {L"%.10d", UTIL_INT},
-      {L"%.100d", -1},
+      {L"%.1d", CJS_Util::DataType::kInt},
+      {L"%.10d", CJS_Util::DataType::kInt},
+      {L"%.100d", CJS_Util::DataType::kInvalid},
 
       // Unexpected characters
-      {L"%ad", -1},
-      {L"%bx", -1},
-      // {L"%cf", -1},
-      // {L"%es", -1},
-      // {L"%gd", -1},
-      {L"%hx", -1},
-      // {L"%if", -1},
-      {L"%js", -1},
-      {L"%@d", -1},
-      {L"%~x", -1},
-      {L"%[f", -1},
-      {L"%\0s", -1},
-      {L"%\nd", -1},
-      {L"%\rx", -1},
-      // {L"%%f", -1},
-      // {L"%  s", -1},
+      {L"%ad", CJS_Util::DataType::kInvalid},
+      {L"%bx", CJS_Util::DataType::kInvalid},
+      // {L"%cf", CJS_Util::DataType::kInvalid},
+      // {L"%es", CJS_Util::DataType::kInvalid},
+      // {L"%gd", CJS_Util::DataType::kInvalid},
+      {L"%hx", CJS_Util::DataType::kInvalid},
+      // {L"%if", CJS_Util::DataType::kInvalid},
+      {L"%js", CJS_Util::DataType::kInvalid},
+      {L"%@d", CJS_Util::DataType::kInvalid},
+      {L"%~x", CJS_Util::DataType::kInvalid},
+      {L"%[f", CJS_Util::DataType::kInvalid},
+      {L"%\0s", CJS_Util::DataType::kInvalid},
+      {L"%\nd", CJS_Util::DataType::kInvalid},
+      {L"%\rx", CJS_Util::DataType::kInvalid},
+      // {L"%%f", CJS_Util::DataType::kInvalid},
+      // {L"%  s", CJS_Util::DataType::kInvalid},
 
       // Combine multiple valid components
-      {L"%+6d", UTIL_INT},
-      {L"% 7x", UTIL_INT},
-      {L"%#9.3f", UTIL_DOUBLE},
-      {L"%10s", UTIL_STRING},
+      {L"%+6d", CJS_Util::DataType::kInt},
+      {L"% 7x", CJS_Util::DataType::kInt},
+      {L"%#9.3f", CJS_Util::DataType::kDouble},
+      {L"%10s", CJS_Util::DataType::kString},
   };
 
   for (size_t i = 0; i < pdfium::size(cases); i++) {