diff --git a/pypy/module/crypt/interp_crypt.py b/pypy/module/crypt/interp_crypt.py
index d227b6a..da969e6 100644
--- a/pypy/module/crypt/interp_crypt.py
+++ b/pypy/module/crypt/interp_crypt.py
@@ -6,7 +6,7 @@ import sys
 if sys.platform.startswith('darwin'):
     eci = ExternalCompilationInfo()
 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)