diff --git a/package/safeclib/safeclib.mk b/package/safeclib/safeclib.mk
index 91b3e26c68..bc58c1a38c 100644
--- a/package/safeclib/safeclib.mk
+++ b/package/safeclib/safeclib.mk
@@ -11,6 +11,7 @@ SAFECLIB_SOURCE = safeclib-$(SAFECLIB_VERSION).tar.xz
 SAFECLIB_LICENSE = MIT
 SAFECLIB_LICENSE_FILES = COPYING
 SAFECLIB_INSTALL_STAGING = YES
+SAFECLIB_CONF_ENV = CFLAGS="$(TARGET_CFLAGS) -std=c99"
 # -fstack-protector-strong is used by default. Disable that so the
 # BR2_SSP_* options in the toolchain wrapper are used instead
 SAFECLIB_CONF_OPTS = --disable-hardening