diff --git a/lib/memdebug.h b/lib/memdebug.h
index 0493bf61bc..2038dc34d3 100644
--- a/lib/memdebug.h
+++ b/lib/memdebug.h
@@ -56,8 +56,6 @@
 #  define ALLOC_SIZE2(n, s)
 #endif
 
-#define CURL_MT_LOGFNAME_BUFSIZE 512
-
 /* Avoid redundant redeclaration warnings with modern compilers, when including
    this header multiple times. */
 #ifndef HEADER_CURL_MEMDEBUG_H_EXTERNS
diff --git a/src/tool_main.c b/src/tool_main.c
index b1135f8628..4fb92d473b 100644
--- a/src/tool_main.c
+++ b/src/tool_main.c
@@ -116,9 +116,9 @@ static void memory_tracking_init(void)
   env = curl_getenv("CURL_MEMDEBUG");
   if(env) {
     /* use the value as filename */
-    char fname[CURL_MT_LOGFNAME_BUFSIZE];
-    if(strlen(env) >= CURL_MT_LOGFNAME_BUFSIZE)
-      env[CURL_MT_LOGFNAME_BUFSIZE-1] = '\0';
+    char fname[512];
+    if(strlen(env) >= sizeof(fname))
+      env[sizeof(fname)-1] = '\0';
     strcpy(fname, env);
     curl_free(env);
     curl_dbg_memdebug(fname);