diff --git a/pkg/front_end/testcases/old_dills/dart2js.version.32.compile.1.dill b/pkg/front_end/testcases/old_dills/dart2js.version.32.compile.1.dill
new file mode 100644
index 00000000000..ce5e225e5fa
Binary files /dev/null and b/pkg/front_end/testcases/old_dills/dart2js.version.32.compile.1.dill differ
diff --git a/pkg/kernel/binary.md b/pkg/kernel/binary.md
index cad20ee8ace..472c73e7799 100644
--- a/pkg/kernel/binary.md
+++ b/pkg/kernel/binary.md
@@ -143,7 +143,7 @@ type CanonicalName {
 
 type ComponentFile {
   UInt32 magic = 0x90ABCDEF;
-  UInt32 formatVersion = 31;
+  UInt32 formatVersion = 32;
   List<String> problemsAsJson; // Described in problems.md.
   Library[] libraries;
   UriSource sourceMap;
@@ -228,7 +228,7 @@ type Name {
 }
 
 type Library {
-  Byte flags (isExternal, isSynthetic);
+  Byte flags (isExternal, isSynthetic, isNonNullableOptedIn);
   UInt languageVersionMajor;
   UInt languageVersionMinor;
   CanonicalNameReference canonicalName;
diff --git a/pkg/kernel/lib/ast.dart b/pkg/kernel/lib/ast.dart
index 3a8463ec6e7..cb04d5887a4 100644
--- a/pkg/kernel/lib/ast.dart
+++ b/pkg/kernel/lib/ast.dart
@@ -330,6 +330,7 @@ class Library extends NamedNode
 
   static const int ExternalFlag = 1 << 0;
   static const int SyntheticFlag = 1 << 1;
+  static const int NonNullableOptedInFlag = 1 << 2;
 
   int flags = 0;
 
@@ -354,6 +355,13 @@ class Library extends NamedNode
     flags = value ? (flags | SyntheticFlag) : (flags & ~SyntheticFlag);
   }
 
+  bool get isNonNullableOptedIn => (flags & NonNullableOptedInFlag) != 0;
+  void set isNonNullableOptedIn(bool value) {
+    flags = value
+        ? (flags | NonNullableOptedInFlag)
+        : (flags & ~NonNullableOptedInFlag);
+  }
+
   String name;
 
   /// Problems in this [Library] encoded as json objects.
diff --git a/pkg/kernel/lib/binary/tag.dart b/pkg/kernel/lib/binary/tag.dart
index dc930734319..0645cb934ce 100644
--- a/pkg/kernel/lib/binary/tag.dart
+++ b/pkg/kernel/lib/binary/tag.dart
@@ -146,7 +146,7 @@ class Tag {
   /// Internal version of kernel binary format.
   /// Bump it when making incompatible changes in kernel binaries.
   /// Keep in sync with runtime/vm/kernel_binary.h, pkg/kernel/binary.md.
-  static const int BinaryFormatVersion = 31;
+  static const int BinaryFormatVersion = 32;
 }
 
 abstract class ConstantTag {
diff --git a/runtime/vm/kernel_binary.h b/runtime/vm/kernel_binary.h
index 009cab20aa1..2a9d614a163 100644
--- a/runtime/vm/kernel_binary.h
+++ b/runtime/vm/kernel_binary.h
@@ -20,7 +20,7 @@ static const uint32_t kMagicProgramFile = 0x90ABCDEFu;
 
 // Both version numbers are inclusive.
 static const uint32_t kMinSupportedKernelFormatVersion = 18;
-static const uint32_t kMaxSupportedKernelFormatVersion = 31;
+static const uint32_t kMaxSupportedKernelFormatVersion = 32;
 
 // Keep in sync with package:kernel/lib/binary/tag.dart
 #define KERNEL_TAG_LIST(V)                                                     \