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)