diff --git a/windows/utils/dputs.c b/windows/utils/dputs.c
index 15b0e4db..f582509a 100644
--- a/windows/utils/dputs.c
+++ b/windows/utils/dputs.c
@@ -11,7 +11,7 @@
 #include "putty.h"
 #include "utils/utils.h"
 
-static FILE *debug_fp = NULL;
+static HANDLE debug_fp = INVALID_HANDLE_VALUE;
 static HANDLE debug_hdl = INVALID_HANDLE_VALUE;
 static int debug_got_console = 0;
 
@@ -25,13 +25,15 @@ void dputs(const char *buf)
             debug_hdl = GetStdHandle(STD_OUTPUT_HANDLE);
         }
     }
-    if (!debug_fp) {
-        debug_fp = fopen("debug.log", "w");
+    if (debug_fp == INVALID_HANDLE_VALUE) {
+        debug_fp = CreateFile("debug.log", GENERIC_WRITE, FILE_SHARE_READ,
+                              NULL, CREATE_ALWAYS, FILE_ATTRIBUTE_NORMAL, NULL);
     }
 
+    if (debug_fp != INVALID_HANDLE_VALUE) {
+        WriteFile(debug_fp, buf, strlen(buf), &dw, NULL);
+    }
     if (debug_hdl != INVALID_HANDLE_VALUE) {
         WriteFile(debug_hdl, buf, strlen(buf), &dw, NULL);
     }
-    fputs(buf, debug_fp);
-    fflush(debug_fp);
 }