diff --git a/src/component/base/DraftScrollPosition.js b/src/component/base/DraftScrollPosition.js
index 3cd25b3ee9..65c17399b1 100644
--- a/src/component/base/DraftScrollPosition.js
+++ b/src/component/base/DraftScrollPosition.js
@@ -8,7 +8,7 @@
  *
  * @providesModule DraftScrollPosition
  * @format
- * @flow
+ * @flow strict
  */
 
 'use strict';
diff --git a/src/component/base/DraftTextAlignment.js b/src/component/base/DraftTextAlignment.js
index 316fd93576..5a1aabb330 100644
--- a/src/component/base/DraftTextAlignment.js
+++ b/src/component/base/DraftTextAlignment.js
@@ -8,7 +8,7 @@
  *
  * @providesModule DraftTextAlignment
  * @format
- * @flow
+ * @flow strict
  */
 
 'use strict';
diff --git a/src/component/handlers/DraftEditorModes.js b/src/component/handlers/DraftEditorModes.js
index 7ac4520446..59f690f9b4 100644
--- a/src/component/handlers/DraftEditorModes.js
+++ b/src/component/handlers/DraftEditorModes.js
@@ -8,7 +8,7 @@
  *
  * @providesModule DraftEditorModes
  * @format
- * @flow
+ * @flow strict
  */
 
 'use strict';
diff --git a/src/component/selection/DraftOffsetKeyPath.js b/src/component/selection/DraftOffsetKeyPath.js
index 15a33625bf..752bed38f2 100644
--- a/src/component/selection/DraftOffsetKeyPath.js
+++ b/src/component/selection/DraftOffsetKeyPath.js
@@ -8,7 +8,7 @@
  *
  * @providesModule DraftOffsetKeyPath
  * @format
- * @flow
+ * @flow strict
  */
 
 'use strict';
diff --git a/src/component/utils/splitTextIntoTextBlocks.js b/src/component/utils/splitTextIntoTextBlocks.js
index 6cc18ae4fb..a8fb3b312d 100644
--- a/src/component/utils/splitTextIntoTextBlocks.js
+++ b/src/component/utils/splitTextIntoTextBlocks.js
@@ -8,7 +8,7 @@
  *
  * @providesModule splitTextIntoTextBlocks
  * @format
- * @flow
+ * @flow strict
  */
 
 'use strict';
diff --git a/src/model/constants/DraftBlockType.js b/src/model/constants/DraftBlockType.js
index 3f27bbfdff..1013fccc8f 100644
--- a/src/model/constants/DraftBlockType.js
+++ b/src/model/constants/DraftBlockType.js
@@ -8,7 +8,7 @@
  *
  * @providesModule DraftBlockType
  * @format
- * @flow
+ * @flow strict
  */
 
 'use strict';
diff --git a/src/model/constants/DraftDragType.js b/src/model/constants/DraftDragType.js
index f2c5887439..5e0d6b95ed 100644
--- a/src/model/constants/DraftDragType.js
+++ b/src/model/constants/DraftDragType.js
@@ -8,7 +8,7 @@
  *
  * @providesModule DraftDragType
  * @format
- * @flow
+ * @flow strict
  */
 
 'use strict';
diff --git a/src/model/constants/DraftEditorCommand.js b/src/model/constants/DraftEditorCommand.js
index bb8b0bffce..c4c26fa6db 100644
--- a/src/model/constants/DraftEditorCommand.js
+++ b/src/model/constants/DraftEditorCommand.js
@@ -8,7 +8,7 @@
  *
  * @providesModule DraftEditorCommand
  * @format
- * @flow
+ * @flow strict
  */
 
 /*eslint-disable no-bitwise*/
diff --git a/src/model/constants/DraftHandleValue.js b/src/model/constants/DraftHandleValue.js
index 29adae5882..804a4057b9 100644
--- a/src/model/constants/DraftHandleValue.js
+++ b/src/model/constants/DraftHandleValue.js
@@ -8,7 +8,7 @@
  *
  * @providesModule DraftHandleValue
  * @format
- * @flow
+ * @flow strict
  */
 
 /*eslint-disable no-bitwise*/
diff --git a/src/model/constants/DraftInsertionType.js b/src/model/constants/DraftInsertionType.js
index 1f80fee362..b4b40f24f5 100644
--- a/src/model/constants/DraftInsertionType.js
+++ b/src/model/constants/DraftInsertionType.js
@@ -8,7 +8,7 @@
  *
  * @providesModule DraftInsertionType
  * @format
- * @flow
+ * @flow strict
  */
 
 'use strict';
diff --git a/src/model/constants/DraftRemovalDirection.js b/src/model/constants/DraftRemovalDirection.js
index 09f4f5bfaf..88dc251bca 100644
--- a/src/model/constants/DraftRemovalDirection.js
+++ b/src/model/constants/DraftRemovalDirection.js
@@ -8,7 +8,7 @@
  *
  * @providesModule DraftRemovalDirection
  * @format
- * @flow
+ * @flow strict
  */
 
 /*eslint-disable no-bitwise*/
diff --git a/src/model/encoding/DraftStringKey.js b/src/model/encoding/DraftStringKey.js
index bbebad6083..fe1af26e51 100644
--- a/src/model/encoding/DraftStringKey.js
+++ b/src/model/encoding/DraftStringKey.js
@@ -8,7 +8,7 @@
  *
  * @providesModule DraftStringKey
  * @format
- * @flow
+ * @flow strict
  */
 
 'use strict';
diff --git a/src/model/encoding/EntityRange.js b/src/model/encoding/EntityRange.js
index f785e0f242..f7d793ac62 100644
--- a/src/model/encoding/EntityRange.js
+++ b/src/model/encoding/EntityRange.js
@@ -8,7 +8,7 @@
  *
  * @providesModule EntityRange
  * @format
- * @flow
+ * @flow strict
  */
 
 'use strict';
diff --git a/src/model/encoding/InlineStyleRange.js b/src/model/encoding/InlineStyleRange.js
index 8847b89d30..0774c9ef21 100644
--- a/src/model/encoding/InlineStyleRange.js
+++ b/src/model/encoding/InlineStyleRange.js
@@ -8,7 +8,7 @@
  *
  * @providesModule InlineStyleRange
  * @format
- * @flow
+ * @flow strict
  */
 
 'use strict';
diff --git a/src/model/encoding/sanitizeDraftText.js b/src/model/encoding/sanitizeDraftText.js
index 86d2cc72d4..95961df748 100644
--- a/src/model/encoding/sanitizeDraftText.js
+++ b/src/model/encoding/sanitizeDraftText.js
@@ -8,7 +8,7 @@
  *
  * @providesModule sanitizeDraftText
  * @format
- * @flow
+ * @flow strict
  */
 
 'use strict';
diff --git a/src/model/immutable/DefaultDraftInlineStyle.js b/src/model/immutable/DefaultDraftInlineStyle.js
index 8410dcaae2..c66bfff49d 100644
--- a/src/model/immutable/DefaultDraftInlineStyle.js
+++ b/src/model/immutable/DefaultDraftInlineStyle.js
@@ -8,7 +8,7 @@
  *
  * @providesModule DefaultDraftInlineStyle
  * @format
- * @flow
+ * @flow strict
  */
 
 'use strict';
diff --git a/src/model/immutable/EditorChangeType.js b/src/model/immutable/EditorChangeType.js
index 7908211397..efd5f9c477 100644
--- a/src/model/immutable/EditorChangeType.js
+++ b/src/model/immutable/EditorChangeType.js
@@ -8,7 +8,7 @@
  *
  * @providesModule EditorChangeType
  * @format
- * @flow
+ * @flow strict
  */
 
 /*eslint-disable no-bitwise*/
diff --git a/src/model/keys/generateRandomKey.js b/src/model/keys/generateRandomKey.js
index 4ee54ee832..3825d5cfff 100644
--- a/src/model/keys/generateRandomKey.js
+++ b/src/model/keys/generateRandomKey.js
@@ -8,7 +8,7 @@
  *
  * @providesModule generateRandomKey
  * @format
- * @flow
+ * @flow strict
  */
 
 'use strict';
diff --git a/src/model/modifier/DraftRange.js b/src/model/modifier/DraftRange.js
index 9b4c945141..28c2b72dfa 100644
--- a/src/model/modifier/DraftRange.js
+++ b/src/model/modifier/DraftRange.js
@@ -8,7 +8,7 @@
  *
  * @providesModule DraftRange
  * @format
- * @flow
+ * @flow strict
  */
 
 'use strict';
diff --git a/src/stubs/ComposedEntityMutability.js b/src/stubs/ComposedEntityMutability.js
index 6fcac07d46..8efb50a934 100644
--- a/src/stubs/ComposedEntityMutability.js
+++ b/src/stubs/ComposedEntityMutability.js
@@ -8,7 +8,7 @@
  *
  * @providesModule ComposedEntityMutability
  * @format
- * @flow
+ * @flow strict
  */
 
 'use strict';
diff --git a/src/stubs/ComposedEntityType.js b/src/stubs/ComposedEntityType.js
index 02aaf1e09c..354802bd99 100644
--- a/src/stubs/ComposedEntityType.js
+++ b/src/stubs/ComposedEntityType.js
@@ -8,7 +8,7 @@
  *
  * @providesModule ComposedEntityType
  * @format
- * @flow
+ * @flow strict
  */
 
 'use strict';
diff --git a/src/stubs/gkx.js b/src/stubs/gkx.js
index 831663e9bc..9d2519e172 100644
--- a/src/stubs/gkx.js
+++ b/src/stubs/gkx.js
@@ -8,7 +8,7 @@
  *
  * @providesModule gkx
  * @format
- * @flow
+ * @flow strict
  */
 
 'use strict';