diff --git a/src/string.cpp b/src/string.cpp
--- a/src/string.cpp
+++ b/src/string.cpp
@@ -120,9 +120,9 @@ char *strecpy(char *dst, const char *src
 
 	if (dst == last && *src != '\0') {
 #if defined(STRGEN) || defined(SETTINGSGEN)
-		error("String too long for destination buffer");
+		error("String too long for destination buffer: %s", src);
 #else /* STRGEN || SETTINGSGEN */
-		Debug(misc, 0, "String too long for destination buffer");
+		Debug(misc, 0, "String too long for destination buffer: {}", src);
 #endif /* STRGEN || SETTINGSGEN */
 	}
 	return dst;
@@ -143,6 +143,16 @@ char *stredup(const char *s, const char 
 	return tmp;
 }
 
+char *str_vfmt(const char *str, va_list va)
+{
+	char buf[4096];
+
+	int len = vseprintf(buf, lastof(buf), str, va);
+	char *p = MallocT<char>(len + 1);
+	memcpy(p, buf, len + 1);
+	return p;
+}
+
 /**
  * Format, "printf", into a newly allocated string.
  * @param str The formatting string.