diff --git a/src/unix/utilsunx.cpp b/src/unix/utilsunx.cpp
index e2696eee7b..f7b9b01140 100644
--- a/src/unix/utilsunx.cpp
+++ b/src/unix/utilsunx.cpp
@@ -96,7 +96,7 @@ void wxUsleep(unsigned long milliseconds)
     // of Solaris has a safe usleep() function but please notice that usleep()
     // is known to lead to crashes in MT programs in Solaris 2.[67] and is not
     // documented as MT-Safe
-    #if defined(__SUN__) && defined(wxUSE_THREADS)
+    #if defined(__SUN__) && wxUSE_THREADS
         #error "usleep() cannot be used in MT programs under Solaris."
     #endif // Sun