diff --git a/kram-profile/Source/KramZipHelper.cpp b/kram-profile/Source/KramZipHelper.cpp
index 42c175e..f653ef2 100644
--- a/kram-profile/Source/KramZipHelper.cpp
+++ b/kram-profile/Source/KramZipHelper.cpp
@@ -25,7 +25,7 @@
 #include <mutex>
 #endif
 
-extern "C" const char* _Nonnull demangleSymbolName(const char* _Nonnull symbolName_) {
+extern "C" const char* _Nullable demangleSymbolName(const char* _Nonnull symbolName_) {
     using namespace NAMESPACE_STL;
     
     // serialize to multiple threads
@@ -53,7 +53,13 @@ extern "C" const char* _Nonnull demangleSymbolName(const char* _Nonnull symbolNa
     }
     else {
         // This will do repeated demangle though.  Maybe should add to table?
-        result = symbolName_;
+        // Swift fails when returning back the string it marshalled back to stuff back
+        // into String(cstring: ...).   Ugh.  So return empty string.
+        // status = -2 on most of the mangled Win clang-cli symbols.  Nice one
+        // Microsoft.
+        //result = symbolName_;
+        
+        result = nullptr;
     }
     
     return result;
diff --git a/kram-profile/Source/KramZipHelperW.h b/kram-profile/Source/KramZipHelperW.h
index bb5659b..304ad78 100644
--- a/kram-profile/Source/KramZipHelperW.h
+++ b/kram-profile/Source/KramZipHelperW.h
@@ -36,5 +36,5 @@ typedef struct ZipEntryW {
 @end
 
 // This is only needed for OptFunction and backend names
-const char* _Nonnull demangleSymbolName(const char* _Nonnull symbolName_);
+const char* _Nullable demangleSymbolName(const char* _Nonnull symbolName_);
 
diff --git a/kram-profile/kram-profile/kram_profileApp.swift b/kram-profile/kram-profile/kram_profileApp.swift
index c15487d..815f168 100644
--- a/kram-profile/kram-profile/kram_profileApp.swift
+++ b/kram-profile/kram-profile/kram_profileApp.swift
@@ -1346,9 +1346,11 @@ func updateBuildTimingTask(_ file: File) throws {
         let event = events[i]
         if event.name == "OptFunction" {
             let detail = event.args!["detail"]!.value as! String
-            let symbolName = String(cString: demangleSymbolName(detail))
-            
-            events[i].args!["detail"] = AnyCodable(symbolName)
+            if let demangledName = demangleSymbolName(detail) {
+                let symbolName = String(cString: demangledName)
+                
+                events[i].args!["detail"] = AnyCodable(symbolName)
+            }
         }
     }
     
@@ -1692,9 +1694,11 @@ func loadFileJS(_ file: File) -> String? {
                 let event = catapultProfile.traceEvents![i]
                 if event.name == "OptFunction" {
                     let detail = event.args!["detail"]!.value as! String
-                    let symbolName = String(cString: demangleSymbolName(detail))
-                    
-                    catapultProfile.traceEvents![i].args!["detail"] = AnyCodable(symbolName)
+                    if let demangledName = demangleSymbolName(detail) {
+                        let symbolName = String(cString: demangledName)
+                        
+                        catapultProfile.traceEvents![i].args!["detail"] = AnyCodable(symbolName)
+                    }
                 }
             }