diff --git a/compiler/packages/babel-plugin-react-compiler/src/HIR/BuildHIR.ts b/compiler/packages/babel-plugin-react-compiler/src/HIR/BuildHIR.ts
index 06fcfbea7ecc0..7fb12d4624c10 100644
--- a/compiler/packages/babel-plugin-react-compiler/src/HIR/BuildHIR.ts
+++ b/compiler/packages/babel-plugin-react-compiler/src/HIR/BuildHIR.ts
@@ -607,6 +607,7 @@ function lowerStatement(
             ),
             consequent: bodyBlock,
             alternate: continuationBlock.id,
+            fallthrough: continuationBlock.id,
             id: makeInstructionId(0),
             loc: stmt.node.loc ?? GeneratedSource,
           },
@@ -656,16 +657,13 @@ function lowerStatement(
         },
         conditionalBlock,
       );
-      /*
-       * The conditional block is empty and exists solely as conditional for
-       * (re)entering or exiting the loop
-       */
       const test = lowerExpressionToTemporary(builder, stmt.get('test'));
       const terminal: BranchTerminal = {
         kind: 'branch',
         test,
         consequent: loopBlock,
         alternate: continuationBlock.id,
+        fallthrough: conditionalBlock.id,
         id: makeInstructionId(0),
         loc: stmt.node.loc ?? GeneratedSource,
       };
@@ -975,6 +973,7 @@ function lowerStatement(
         test,
         consequent: loopBlock,
         alternate: continuationBlock.id,
+        fallthrough: conditionalBlock.id,
         id: makeInstructionId(0),
         loc,
       };
@@ -1118,6 +1117,7 @@ function lowerStatement(
           consequent: loopBlock,
           alternate: continuationBlock.id,
           loc: stmt.node.loc ?? GeneratedSource,
+          fallthrough: continuationBlock.id,
         },
         continuationBlock,
       );
@@ -1203,6 +1203,7 @@ function lowerStatement(
           test,
           consequent: loopBlock,
           alternate: continuationBlock.id,
+          fallthrough: continuationBlock.id,
           loc: stmt.node.loc ?? GeneratedSource,
         },
         continuationBlock,
@@ -1800,6 +1801,7 @@ function lowerExpression(
           test: {...testPlace},
           consequent: consequentBlock,
           alternate: alternateBlock,
+          fallthrough: continuationBlock.id,
           id: makeInstructionId(0),
           loc: exprLoc,
         },
@@ -1878,6 +1880,7 @@ function lowerExpression(
           test: {...leftPlace},
           consequent,
           alternate,
+          fallthrough: continuationBlock.id,
           id: makeInstructionId(0),
           loc: exprLoc,
         },
@@ -2611,6 +2614,7 @@ function lowerOptionalMemberExpression(
       test: {...object},
       consequent: consequent.id,
       alternate,
+      fallthrough: continuationBlock.id,
       id: makeInstructionId(0),
       loc,
     };
@@ -2750,6 +2754,7 @@ function lowerOptionalCallExpression(
       test: {...testPlace},
       consequent: consequent.id,
       alternate,
+      fallthrough: continuationBlock.id,
       id: makeInstructionId(0),
       loc,
     };
@@ -4025,6 +4030,7 @@ function lowerAssignment(
           test: {...test},
           consequent,
           alternate,
+          fallthrough: continuationBlock.id,
           id: makeInstructionId(0),
           loc,
         },
diff --git a/compiler/packages/babel-plugin-react-compiler/src/HIR/HIR.ts b/compiler/packages/babel-plugin-react-compiler/src/HIR/HIR.ts
index 3bc7b135b6ced..3a04a4c3c9dce 100644
--- a/compiler/packages/babel-plugin-react-compiler/src/HIR/HIR.ts
+++ b/compiler/packages/babel-plugin-react-compiler/src/HIR/HIR.ts
@@ -491,7 +491,7 @@ export type BranchTerminal = {
   alternate: BlockId;
   id: InstructionId;
   loc: SourceLocation;
-  fallthrough?: never;
+  fallthrough: BlockId;
 };
 
 export type SwitchTerminal = {
diff --git a/compiler/packages/babel-plugin-react-compiler/src/HIR/visitors.ts b/compiler/packages/babel-plugin-react-compiler/src/HIR/visitors.ts
index 0df8478b39c45..904b7a4038dec 100644
--- a/compiler/packages/babel-plugin-react-compiler/src/HIR/visitors.ts
+++ b/compiler/packages/babel-plugin-react-compiler/src/HIR/visitors.ts
@@ -660,11 +660,13 @@ export function mapTerminalSuccessors(
     case 'branch': {
       const consequent = fn(terminal.consequent);
       const alternate = fn(terminal.alternate);
+      const fallthrough = fn(terminal.fallthrough);
       return {
         kind: 'branch',
         test: terminal.test,
         consequent,
         alternate,
+        fallthrough,
         id: makeInstructionId(0),
         loc: terminal.loc,
       };
@@ -883,7 +885,6 @@ export function terminalHasFallthrough<
 >(terminal: T): terminal is U {
   switch (terminal.kind) {
     case 'maybe-throw':
-    case 'branch':
     case 'goto':
     case 'return':
     case 'throw':
@@ -892,6 +893,7 @@ export function terminalHasFallthrough<
       const _: undefined = terminal.fallthrough;
       return false;
     }
+    case 'branch':
     case 'try':
     case 'do-while':
     case 'for-of':
diff --git a/compiler/packages/babel-plugin-react-compiler/src/Inference/DropManualMemoization.ts b/compiler/packages/babel-plugin-react-compiler/src/Inference/DropManualMemoization.ts
index c580b3e8b759f..fdd9bcc968aef 100644
--- a/compiler/packages/babel-plugin-react-compiler/src/Inference/DropManualMemoization.ts
+++ b/compiler/packages/babel-plugin-react-compiler/src/Inference/DropManualMemoization.ts
@@ -42,6 +42,7 @@ type IdentifierSidemap = {
   react: Set<IdentifierId>;
   maybeDepsLists: Map<IdentifierId, Array<Place>>;
   maybeDeps: Map<IdentifierId, ManualMemoDependency>;
+  optionals: Set<IdentifierId>;
 };
 
 /**
@@ -52,6 +53,7 @@ type IdentifierSidemap = {
 export function collectMaybeMemoDependencies(
   value: InstructionValue,
   maybeDeps: Map<IdentifierId, ManualMemoDependency>,
+  optional: boolean,
 ): ManualMemoDependency | null {
   switch (value.kind) {
     case 'LoadGlobal': {
@@ -69,7 +71,7 @@ export function collectMaybeMemoDependencies(
         return {
           root: object.root,
           // TODO: determine if the access is optional
-          path: [...object.path, {property: value.property, optional: false}],
+          path: [...object.path, {property: value.property, optional}],
         };
       }
       break;
@@ -162,7 +164,11 @@ function collectTemporaries(
       break;
     }
   }
-  const maybeDep = collectMaybeMemoDependencies(value, sidemap.maybeDeps);
+  const maybeDep = collectMaybeMemoDependencies(
+    value,
+    sidemap.maybeDeps,
+    sidemap.optionals.has(lvalue.identifier.id),
+  );
   // We don't expect named lvalues during this pass (unlike ValidatePreservingManualMemo)
   if (maybeDep != null) {
     sidemap.maybeDeps.set(lvalue.identifier.id, maybeDep);
@@ -338,12 +344,14 @@ export function dropManualMemoization(func: HIRFunction): void {
     func.env.config.validatePreserveExistingMemoizationGuarantees ||
     func.env.config.validateNoSetStateInRender ||
     func.env.config.enablePreserveExistingMemoizationGuarantees;
+  const optionals = findOptionalPlaces(func);
   const sidemap: IdentifierSidemap = {
     functions: new Map(),
     manualMemos: new Map(),
     react: new Set(),
     maybeDeps: new Map(),
     maybeDepsLists: new Map(),
+    optionals,
   };
   let nextManualMemoId = 0;
 
@@ -476,3 +484,46 @@ export function dropManualMemoization(func: HIRFunction): void {
     }
   }
 }
+
+function findOptionalPlaces(fn: HIRFunction): Set<IdentifierId> {
+  const optionals = new Set<IdentifierId>();
+  for (const [, block] of fn.body.blocks) {
+    if (block.terminal.kind === 'optional') {
+      const optionalTerminal = block.terminal;
+      let testBlock = fn.body.blocks.get(block.terminal.test)!;
+      loop: while (true) {
+        const terminal = testBlock.terminal;
+        switch (terminal.kind) {
+          case 'branch': {
+            if (terminal.fallthrough === optionalTerminal.fallthrough) {
+              // found it
+              const consequent = fn.body.blocks.get(terminal.consequent)!;
+              const last = consequent.instructions.at(-1);
+              if (last !== undefined && last.value.kind === 'StoreLocal') {
+                optionals.add(last.value.value.identifier.id);
+              }
+              break loop;
+            } else {
+              testBlock = fn.body.blocks.get(terminal.fallthrough)!;
+            }
+            break;
+          }
+          case 'optional':
+          case 'logical':
+          case 'sequence':
+          case 'ternary': {
+            testBlock = fn.body.blocks.get(terminal.fallthrough)!;
+            break;
+          }
+          default: {
+            CompilerError.invariant(false, {
+              reason: `Unexpected terminal in optional`,
+              loc: terminal.loc,
+            });
+          }
+        }
+      }
+    }
+  }
+  return optionals;
+}
diff --git a/compiler/packages/babel-plugin-react-compiler/src/ReactiveScopes/AlignReactiveScopesToBlockScopesHIR.ts b/compiler/packages/babel-plugin-react-compiler/src/ReactiveScopes/AlignReactiveScopesToBlockScopesHIR.ts
index 6517918d02e16..3e8329679cfe2 100644
--- a/compiler/packages/babel-plugin-react-compiler/src/ReactiveScopes/AlignReactiveScopesToBlockScopesHIR.ts
+++ b/compiler/packages/babel-plugin-react-compiler/src/ReactiveScopes/AlignReactiveScopesToBlockScopesHIR.ts
@@ -140,7 +140,7 @@ export function alignReactiveScopesToBlockScopesHIR(fn: HIRFunction): void {
     }
 
     const fallthrough = terminalFallthrough(terminal);
-    if (fallthrough !== null) {
+    if (fallthrough !== null && terminal.kind !== 'branch') {
       /*
        * Any currently active scopes that overlaps the block-fallthrough range
        * need their range extended to at least the first instruction of the
diff --git a/compiler/packages/babel-plugin-react-compiler/src/Validation/ValidatePreservedManualMemoization.ts b/compiler/packages/babel-plugin-react-compiler/src/Validation/ValidatePreservedManualMemoization.ts
index 5a9a947d88bfd..6d948fad9711a 100644
--- a/compiler/packages/babel-plugin-react-compiler/src/Validation/ValidatePreservedManualMemoization.ts
+++ b/compiler/packages/babel-plugin-react-compiler/src/Validation/ValidatePreservedManualMemoization.ts
@@ -167,7 +167,10 @@ function compareDeps(
 
   let isSubpath = true;
   for (let i = 0; i < Math.min(inferred.path.length, source.path.length); i++) {
-    if (inferred.path[i].property !== source.path[i].property) {
+    if (
+      inferred.path[i].property !== source.path[i].property ||
+      inferred.path[i].optional !== source.path[i].optional
+    ) {
       isSubpath = false;
       break;
     }
@@ -339,7 +342,11 @@ class Visitor extends ReactiveFunctionVisitor<VisitorState> {
         return null;
       }
       default: {
-        const dep = collectMaybeMemoDependencies(value, this.temporaries);
+        const dep = collectMaybeMemoDependencies(
+          value,
+          this.temporaries,
+          false,
+        );
         if (value.kind === 'StoreLocal' || value.kind === 'StoreContext') {
           const storeTarget = value.lvalue.place;
           state.manualMemoState?.decls.add(