diff --git a/lib/AST/ASTContext.cpp b/lib/AST/ASTContext.cpp
index 0a2b122d693b4..8e5cf912970d9 100644
--- a/lib/AST/ASTContext.cpp
+++ b/lib/AST/ASTContext.cpp
@@ -1383,6 +1383,9 @@ FuncDecl *ASTContext::getMakeInvocationEncoderOnDistributedActorSystem(
 FuncDecl *
 ASTContext::getRecordGenericSubstitutionOnDistributedInvocationEncoder(
     NominalTypeDecl *nominal) const {
+  if (!nominal)
+    return nullptr;
+
   for (auto result : nominal->lookupDirect(Id_recordGenericSubstitution)) {
     auto *func = dyn_cast<FuncDecl>(result);
     if (func &&
@@ -1396,6 +1399,9 @@ ASTContext::getRecordGenericSubstitutionOnDistributedInvocationEncoder(
 
 AbstractFunctionDecl *ASTContext::getRecordArgumentOnDistributedInvocationEncoder(
     NominalTypeDecl *nominal) const {
+  if (!nominal)
+    return nullptr;
+
   return evaluateOrDefault(
       nominal->getASTContext().evaluator,
       GetDistributedTargetInvocationEncoderRecordArgumentFunctionRequest{nominal},
@@ -1404,6 +1410,9 @@ AbstractFunctionDecl *ASTContext::getRecordArgumentOnDistributedInvocationEncode
 
 AbstractFunctionDecl *ASTContext::getRecordReturnTypeOnDistributedInvocationEncoder(
     NominalTypeDecl *nominal) const {
+  if (!nominal)
+    return nullptr;
+
   return evaluateOrDefault(
       nominal->getASTContext().evaluator,
       GetDistributedTargetInvocationEncoderRecordReturnTypeFunctionRequest{nominal},
@@ -1412,6 +1421,9 @@ AbstractFunctionDecl *ASTContext::getRecordReturnTypeOnDistributedInvocationEnco
 
 AbstractFunctionDecl *ASTContext::getRecordErrorTypeOnDistributedInvocationEncoder(
     NominalTypeDecl *nominal) const {
+  if (!nominal)
+    return nullptr;
+
   return evaluateOrDefault(
       nominal->getASTContext().evaluator,
       GetDistributedTargetInvocationEncoderRecordErrorTypeFunctionRequest{nominal},
@@ -1420,6 +1432,9 @@ AbstractFunctionDecl *ASTContext::getRecordErrorTypeOnDistributedInvocationEncod
 
 AbstractFunctionDecl *ASTContext::getDecodeNextArgumentOnDistributedInvocationDecoder(
     NominalTypeDecl *nominal) const {
+  if (!nominal)
+    return nullptr;
+
   return evaluateOrDefault(
       nominal->getASTContext().evaluator,
       GetDistributedTargetInvocationDecoderDecodeNextArgumentFunctionRequest{nominal},
@@ -1428,6 +1443,9 @@ AbstractFunctionDecl *ASTContext::getDecodeNextArgumentOnDistributedInvocationDe
 
 AbstractFunctionDecl *ASTContext::getOnReturnOnDistributedTargetInvocationResultHandler(
     NominalTypeDecl *nominal) const {
+  if (!nominal)
+    return nullptr;
+
   return evaluateOrDefault(
       nominal->getASTContext().evaluator,
       GetDistributedTargetInvocationResultHandlerOnReturnFunctionRequest{nominal},
diff --git a/test/Distributed/distributed_imcomplete_system_dont_crash.swift b/test/Distributed/distributed_imcomplete_system_dont_crash.swift
index a2cc7d2ca3772..e4f5d3e7f9dce 100644
--- a/test/Distributed/distributed_imcomplete_system_dont_crash.swift
+++ b/test/Distributed/distributed_imcomplete_system_dont_crash.swift
@@ -36,4 +36,12 @@ public final class CompletelyHollowActorSystem: DistributedActorSystem {
     // expected-error@-1{{type 'CompletelyHollowActorSystem.ResultHandler' does not conform to protocol 'DistributedTargetInvocationResultHandler'}}
   }
 
+}
+
+public final class CompletelyHollowActorSystem_NotEvenTypes: DistributedActorSystem {
+  // expected-error@-1{{type 'CompletelyHollowActorSystem_NotEvenTypes' does not conform to protocol 'DistributedActorSystem'}}
+  // expected-error@-2{{class 'CompletelyHollowActorSystem_NotEvenTypes' is missing witness for protocol requirement 'remoteCallVoid'}}
+  // expected-error@-3{{class 'CompletelyHollowActorSystem_NotEvenTypes' is missing witness for protocol requirement 'remoteCall'}}
+  // expected-note@-4{{protocol 'DistributedActorSystem' requires function 'remoteCall' with signature:}}
+  // expected-note@-5{{protocol 'DistributedActorSystem' requires function 'remoteCallVoid' with signature:}}
 }
\ No newline at end of file