diff --git a/pypy/module/crypt/interp_crypt.py b/pypy/module/crypt/interp_crypt.py
index bd13f6f..1022c9e 100644
--- a/pypy/module/crypt/interp_crypt.py
+++ b/pypy/module/crypt/interp_crypt.py
@@ -9,7 +9,7 @@ elif sys.platform.startswith('linux'):
     # crypt() is defined only in crypt.h on some Linux variants (eg. Fedora 28)
     eci = ExternalCompilationInfo(libraries=['crypt'], includes=["crypt.h"])
 else:
-    eci = ExternalCompilationInfo(libraries=['crypt'])
+    eci = ExternalCompilationInfo(libraries=['crypt'], includes=['crypt.h'])
 c_crypt = rffi.llexternal('crypt', [rffi.CCHARP, rffi.CCHARP], rffi.CCHARP,
                           compilation_info=eci, releasegil=False)