diff --git a/lib/curl_setup.h b/lib/curl_setup.h
index 34a37dd0f3..f4640b922f 100644
--- a/lib/curl_setup.h
+++ b/lib/curl_setup.h
@@ -1217,12 +1217,14 @@ typedef struct sockaddr_un {
 #  define CURL_INLINE /* empty */
 #endif
 
-#if defined(__STDC_VERSION__) && __STDC_VERSION__ >= 199901L
-#define CURL_HAVE_C99
+/* Detect if compiler supports C99 variadic macros */
+#if (defined(__STDC_VERSION__) && __STDC_VERSION__ >= 199901L) || \
+  defined(_MSC_VER)
+#define CURL_HAVE_MACRO_VARARG
 #endif
 
-#if (defined(CURL_HAVE_C99) && !defined(CURL_DISABLE_VERBOSE_STRINGS)) || \
-  !defined(CURL_HAVE_C99)
+#if !defined(CURL_HAVE_MACRO_VARARG) || \
+  (defined(CURL_HAVE_MACRO_VARARG) && !defined(CURL_DISABLE_VERBOSE_STRINGS))
 #define CURLVERBOSE
 #define VERBOSE(x) x
 #define NOVERBOSE(x) Curl_nop_stmt
diff --git a/lib/curl_trc.h b/lib/curl_trc.h
index c626a97e68..58903844ac 100644
--- a/lib/curl_trc.h
+++ b/lib/curl_trc.h
@@ -129,7 +129,7 @@ void Curl_trc_ws(struct Curl_easy *data,
 #define CURL_TRC_TIMER_is_verbose(data) \
   Curl_trc_ft_is_verbose(data, &Curl_trc_feat_timer)
 
-#if defined(CURL_HAVE_C99) && !defined(CURL_DISABLE_VERBOSE_STRINGS)
+#if defined(CURL_HAVE_MACRO_VARARG) && !defined(CURL_DISABLE_VERBOSE_STRINGS)
 #define infof(data, ...)             \
   do {                               \
     if(Curl_trc_is_verbose(data))    \
@@ -202,7 +202,7 @@ void Curl_trc_ws(struct Curl_easy *data,
   } while(0)
 #endif /* !CURL_DISABLE_WEBSOCKETS && !CURL_DISABLE_HTTP */
 
-#elif defined(CURL_HAVE_C99) && defined(CURL_DISABLE_VERBOSE_STRINGS)
+#elif defined(CURL_HAVE_MACRO_VARARG) && defined(CURL_DISABLE_VERBOSE_STRINGS)
 
 #define infof(data, ...) \
   do {                   \
@@ -265,7 +265,7 @@ void Curl_trc_ws(struct Curl_easy *data,
   } while(0)
 #endif
 
-#else /* !CURL_HAVE_C99 */
+#else /* !CURL_HAVE_MACRO_VARARG */
 
 #define infof          Curl_infof
 #define CURL_TRC_M     Curl_trc_multi
@@ -291,7 +291,7 @@ void Curl_trc_ws(struct Curl_easy *data,
 #define CURL_TRC_WS    Curl_trc_ws
 #endif
 
-#endif /* !CURL_HAVE_C99 */
+#endif /* CURL_HAVE_MACRO_VARARG */
 
 #ifdef CURLVERBOSE
 extern struct curl_trc_feat Curl_trc_feat_multi;