diff --git a/renderdoc/os/win32/win32_stringio.cpp b/renderdoc/os/win32/win32_stringio.cpp
index 87d6cce0c..f593c3db4 100644
--- a/renderdoc/os/win32/win32_stringio.cpp
+++ b/renderdoc/os/win32/win32_stringio.cpp
@@ -238,7 +238,7 @@ namespace FileIO
 		va_list args;
 		va_start(args, fmt);
 
-		int ret = ::fprintf(f, fmt, args);
+		int ret = ::vfprintf(f, fmt, args);
 
 		va_end(args);