diff --git a/clang/include/clang/Serialization/SourceLocationEncoding.h b/clang/include/clang/Serialization/SourceLocationEncoding.h
index 33ca1728fa479..85a7379a5fb55 100644
--- a/clang/include/clang/Serialization/SourceLocationEncoding.h
+++ b/clang/include/clang/Serialization/SourceLocationEncoding.h
@@ -48,6 +48,9 @@ class SourceLocationEncoding {
   using UIntTy = SourceLocation::UIntTy;
   constexpr static unsigned UIntBits = CHAR_BIT * sizeof(UIntTy);
 
+  // The maximum number of bits we use for the encoding.
+  constexpr static unsigned EncodingBits = UIntBits + 1;
+
   static UIntTy encodeRaw(UIntTy Raw) {
     return (Raw << 1) | (Raw >> (UIntBits - 1));
   }
@@ -179,20 +182,20 @@ SourceLocationEncoding::encode(SourceLocation Loc, UIntTy BaseOffset,
 
   // 16 bits should be sufficient to store the module file index.
   assert(BaseModuleFileIndex < (1 << 16));
-  Encoded |= (RawLocEncoding)BaseModuleFileIndex << 32;
+  Encoded |= (RawLocEncoding)BaseModuleFileIndex << EncodingBits;
   return Encoded;
 }
 inline std::pair<SourceLocation, unsigned>
 SourceLocationEncoding::decode(RawLocEncoding Encoded,
                                SourceLocationSequence *Seq) {
-  unsigned ModuleFileIndex = Encoded >> 32;
+  unsigned ModuleFileIndex = Encoded >> EncodingBits;
 
   if (!ModuleFileIndex)
     return {Seq ? Seq->decode(Encoded)
                 : SourceLocation::getFromRawEncoding(decodeRaw(Encoded)),
             ModuleFileIndex};
 
-  Encoded &= llvm::maskTrailingOnes<RawLocEncoding>(32);
+  Encoded &= llvm::maskTrailingOnes<RawLocEncoding>(EncodingBits);
   SourceLocation Loc = SourceLocation::getFromRawEncoding(decodeRaw(Encoded));
 
   return {Loc, ModuleFileIndex};
diff --git a/clang/unittests/Serialization/SourceLocationEncodingTest.cpp b/clang/unittests/Serialization/SourceLocationEncodingTest.cpp
index c80a8fd0e52b1..b21035af47cfc 100644
--- a/clang/unittests/Serialization/SourceLocationEncodingTest.cpp
+++ b/clang/unittests/Serialization/SourceLocationEncodingTest.cpp
@@ -104,6 +104,8 @@ TEST(SourceLocationEncoding, Sequence) {
 
   roundTrip(
       {123 | MacroBit, 1, 9, Biggest, Big, Big + 1, 0, MacroBit | Big, 0});
+
+  roundTrip({1, (1u << 30) + 1});
 }
 
 } // namespace