diff --git a/internal/c/parts/core/src/freeglut_internal.h b/internal/c/parts/core/src/freeglut_internal.h
index eda9342b8..60532562f 100644
--- a/internal/c/parts/core/src/freeglut_internal.h
+++ b/internal/c/parts/core/src/freeglut_internal.h
@@ -138,9 +138,9 @@
 #ifdef HAVE_SYS_TYPES_H
 #    include <sys/types.h>
 #endif
-#ifdef HAVE_UNISTD_H
-#    include <unistd.h>
-#endif
+
+#include <unistd.h>
+
 #ifdef TIME_WITH_SYS_TIME
 #    include <sys/time.h>
 #    include <time.h>