diff --git a/c-programming/io/freadln.c b/c-programming/io/freadln.c
index d5bb2cb..6f7c867 100644
--- a/c-programming/io/freadln.c
+++ b/c-programming/io/freadln.c
@@ -78,14 +78,14 @@ int freadln(FILE* f, char** output, size_t* length_out) {
 #ifdef TEST
 # if defined(_WIN32) || defined(WIN32)
 #  include <windows.h>
-#  define SLEEP_FN Sleep
+#  define SLEEP_FN(x) Sleep((DWORD) x)
 #  define DO_SLEEP 1
 # elif defined(__CYGWIN__) || defined(__unix__) || defined(__APPLE__) && \
        defined(__MACH__) || defined(__linux__) || defined(__FreeBSD__) || \
        defined(__NetBSD__) || defined(__OpenBSD__) || defined(__bsdi__) || \
        defined(__DragonFly__) || defined(__MINGW32__) || defined(__MINGW64__)
 #  include <unistd.h>
-#  define SLEEP_FN usleep
+#  define SLEEP_FN(x) usleep((x) * 1000ULL)
 #  define DO_SLEEP 1
 # else
 #  define SLEEP_FN(...)