diff --git a/src/assert.cpp b/src/assert.cpp
index 860484616..3c88b0664 100644
--- a/src/assert.cpp
+++ b/src/assert.cpp
@@ -145,7 +145,7 @@ TORRENT_EXPORT void print_backtrace(char* out, int len, int max_depth)
 
 TORRENT_EXPORT void print_backtrace(char* out, int len, int max_depth)
 {
-	typedef USHORT (*RtlCaptureStackBackTrace_t)(
+	typedef USHORT (WINAPI *RtlCaptureStackBackTrace_t)(
 		__in ULONG FramesToSkip,
 		__in ULONG FramesToCapture,
 		__out PVOID *BackTrace,