diff --git a/include/swift/AST/ASTBridging.h b/include/swift/AST/ASTBridging.h
index 50985bf7ee7ef..3d26622667e4b 100644
--- a/include/swift/AST/ASTBridging.h
+++ b/include/swift/AST/ASTBridging.h
@@ -40,9 +40,10 @@ typedef enum ENUM_EXTENSIBILITY_ATTR(open) BridgedDiagID : uint32_t {
 #include "swift/AST/DiagnosticsAll.def"
 } BridgedDiagID;
 
-struct BridgedDiagnosticEngine {
+// Must match the definition of BridgedDiagnosticEngine in CASTBridging.h.
+typedef struct {
   void * _Nonnull object;
-};
+} BridgedDiagnosticEngine;
 
 struct BridgedOptionalDiagnosticEngine {
   void *_Nullable object;
@@ -66,7 +67,7 @@ class BridgedDiagnosticArgument {
 };
 
 class BridgedDiagnosticFixIt {
-  int64_t storage[6];
+  int64_t storage[7];
 
 public:
 #ifdef USED_IN_CPP_SOURCE
diff --git a/lib/AST/ASTBridging.cpp b/lib/AST/ASTBridging.cpp
index a6d8a42ab3d2e..db58aaa98fe1b 100644
--- a/lib/AST/ASTBridging.cpp
+++ b/lib/AST/ASTBridging.cpp
@@ -35,7 +35,7 @@ BridgedDiagnosticArgument::BridgedDiagnosticArgument(BridgedStringRef s)
   : BridgedDiagnosticArgument(DiagnosticArgument(s.get())) {}
 
 static_assert(sizeof(BridgedDiagnosticFixIt) >= sizeof(DiagnosticInfo::FixIt),
-              "BridgedDiagnosticArgument has wrong size");
+              "BridgedDiagnosticFixIt has wrong size");
 
 static SourceLoc getSourceLoc(BridgedSourceLoc bridgedLoc) {
   return SourceLoc(llvm::SMLoc::getFromPointer(bridgedLoc.getLoc()));