diff --git a/sys/opencrypto/cryptodev.h b/sys/opencrypto/cryptodev.h
--- a/sys/opencrypto/cryptodev.h
+++ b/sys/opencrypto/cryptodev.h
@@ -71,6 +71,7 @@
 #include <sys/_task.h>
 #include <sys/libkern.h>
 #include <sys/time.h>
+#include <sys/mbuf.h>
 #endif
 
 /* Some initial values */
@@ -489,6 +490,7 @@
 static __inline void
 _crypto_use_mbuf(struct crypto_buffer *cb, struct mbuf *m)
 {
+	MPASS(M_WRITABLE(m));
 	cb->cb_mbuf = m;
 	cb->cb_type = CRYPTO_BUF_MBUF;
 }
@@ -532,6 +534,7 @@
 static __inline void
 crypto_use_single_mbuf(struct cryptop *crp, struct mbuf *m)
 {
+	MPASS(M_WRITABLE(m));
 	_crypto_use_single_mbuf(&crp->crp_buf, m);
 }