diff --git a/stdlib/public/Concurrency/Error.cpp b/stdlib/public/Concurrency/Error.cpp
index 083e75cd562..f9b9c56f489 100644
--- a/stdlib/public/Concurrency/Error.cpp
+++ b/stdlib/public/Concurrency/Error.cpp
@@ -10,6 +10,7 @@
 //
 //===----------------------------------------------------------------------===//
 
+#include "swift/Runtime/Portability.h"
 #include "swift/Threading/Errors.h"
 #include <atomic>
 #include <cstdio>
@@ -32,10 +33,8 @@ SWIFT_VFORMAT(2)
 void swift::swift_Concurrency_fatalErrorv(uint32_t flags, const char *format,
                                           va_list val) {
 #if !SWIFT_CONCURRENCY_EMBEDDED
-  // TODO: copy swift_vasprintf() so we can capture the formatted log message
-  const char *log = format;
-
-  vfprintf(stderr, format, val);
+  char *log = nullptr;
+  swift_vasprintf(&log, format, val);
 
   if (&_swift_willAbort != nullptr) {
     auto handler = _swift_willAbort.exchange(nullptr, std::memory_order_acq_rel);
@@ -43,6 +42,8 @@ void swift::swift_Concurrency_fatalErrorv(uint32_t flags, const char *format,
       (* handler)(flags, log, nullptr);
     }
   }
+
+  fputs(log, stderr);
 #else
   vprintf(format, val);
 #endif
diff --git a/stdlib/public/runtime/Errors.cpp b/stdlib/public/runtime/Errors.cpp
index da4f48b0c5e..05ce31801fa 100644
--- a/stdlib/public/runtime/Errors.cpp
+++ b/stdlib/public/runtime/Errors.cpp
@@ -420,11 +420,8 @@ void swift::swift_reportError(uint32_t flags,
 // Report a fatal error to system console, stderr, and crash logs, then abort.
 SWIFT_NORETURN void swift::fatalErrorv(uint32_t flags, const char *format,
                                        va_list args) {
-  char *log;
-#pragma GCC diagnostic push
-#pragma GCC diagnostic ignored "-Wuninitialized"
+  char *log = nullptr;
   swift_vasprintf(&log, format, args);
-#pragma GCC diagnostic pop
 
   swift_reportError(flags, log);