diff --git a/package/python-pycryptodomex/python-pycryptodomex.mk b/package/python-pycryptodomex/python-pycryptodomex.mk
index 3790aa4787..d6eb2a9513 100644
--- a/package/python-pycryptodomex/python-pycryptodomex.mk
+++ b/package/python-pycryptodomex/python-pycryptodomex.mk
@@ -13,5 +13,8 @@ PYTHON_PYCRYPTODOMEX_LICENSE = \
 	Public Domain (pycrypto original code)
 PYTHON_PYCRYPTODOMEX_LICENSE_FILES = LICENSE.rst Doc/LEGAL/COPYRIGHT.pycrypto
 
+PYTHON_PYCRYPTODOMEX_ENV = CFLAGS="$(TARGET_CFLAGS) -std=c99"
+HOST_PYTHON_PYCRYPTODOMEX_ENV = CFLAGS="$(HOST_CFLAGS) -std=c99"
+
 $(eval $(python-package))
 $(eval $(host-python-package))