diff --git a/modules/Kconfig.civetweb b/modules/Kconfig.civetweb
index 663081b5fc4..8e357692bd5 100644
--- a/modules/Kconfig.civetweb
+++ b/modules/Kconfig.civetweb
@@ -3,5 +3,11 @@
 
 config CIVETWEB
 	bool "Civetweb Support"
+	# The CONFIG_NET_TCP_ISN_RFC6528 option would pull in mbedtls,
+	# and there are include file issues if CONFIG_POSIX_API is set.
+	# Because Civetweb sets the POSIX API option in the samples,
+	# make sure that we do not try to use Civetweb if the TCP ISN
+	# option is set.
+	depends on !NET_TCP_ISN_RFC6528
 	help
 	  This option enables the civetweb HTTP API.