diff --git a/cmdline/snapraid.c b/cmdline/snapraid.c
index be45fa7b..0625692e 100644
--- a/cmdline/snapraid.c
+++ b/cmdline/snapraid.c
@@ -1061,6 +1061,8 @@ int snapraid_main(int argc, char* argv[])
 		}
 	}
 
+	msg_fatal_stderr = !opt.gui;
+
 	os_init(OS_INIT_OPT_AVOID_SLEEP | (opt.force_scan_winfind ? OS_INIT_OPT_WINFIND : 0));
 	app_init();
 	raid_init();
diff --git a/cmdline/support.c b/cmdline/support.c
index dd5fe9e4..62188239 100644
--- a/cmdline/support.c
+++ b/cmdline/support.c
@@ -293,6 +293,7 @@ void log_error_errno(int err, const char* name)
 /* print */
 
 int msg_level = 0;
+int msg_fatal_stderr = 1;
 FILE* stdlog = 0;
 int msg_line_prev = 0; /**< Previous line width on stdout */
 int msg_line_curr = 0; /**< Current line width on stdout */
@@ -393,15 +394,18 @@ void vlog_fatal(int err, const char* format, va_list ap, const char* post)
 		fflush(stdlog);
 	}
 
-	va_list ap_copy2;
-	va_copy(ap_copy2, ap);
-	vmsg(stderr, format, ap_copy2);
-	va_end(ap_copy2);
+	/* GUI consumers read tagged fatal messages from the log and must not receive a duplicate raw copy. */
+	if (!stdlog || msg_fatal_stderr) {
+		va_list ap_copy2;
+		va_copy(ap_copy2, ap);
+		vmsg(stderr, format, ap_copy2);
+		va_end(ap_copy2);
 
-	if (post)
-		msg(stderr, "%s", post);
+		if (post)
+			msg(stderr, "%s", post);
 
-	fflush(stderr);
+		fflush(stderr);
+	}
 
 	unlock_msg();
 }
diff --git a/cmdline/support.h b/cmdline/support.h
index e997b7e0..dbc551a2 100644
--- a/cmdline/support.h
+++ b/cmdline/support.h
@@ -92,7 +92,8 @@ typedef void log_ptr(int err, const char* format, ...) __attribute__((format(att
  *
  * Messages printed before an early termination.
  *
- * These messages go in the log file and in stderr unconditionally.
+ * These messages go in the log file and in stderr, except in GUI mode
+ * when a log is configured, where only the tagged log message is emitted.
  */
 void vlog_fatal(int err, const char* format, va_list ap, const char* post);
 void log_fatal(int err, const char* format, ...) __attribute__((format(attribute_printf, 2, 3)));
@@ -176,6 +177,11 @@ typedef void msg_ptr(const char* format, ...) __attribute__((format(attribute_pr
  */
 extern int msg_level;
 
+/**
+ * Emit fatal messages on stderr also when a log is configured.
+ */
+extern int msg_fatal_stderr;
+
 /**
  * State messages.
  *