diff --git a/src/coap_gnutls.c b/src/coap_gnutls.c
index 8cf73bfa..0a693eaa 100644
--- a/src/coap_gnutls.c
+++ b/src/coap_gnutls.c
@@ -2964,7 +2964,8 @@ coap_digest_setup(void) {
 
 void
 coap_digest_free(coap_digest_ctx_t *digest_ctx) {
-  gnutls_hash_deinit(digest_ctx, NULL);
+  if (digest_ctx)
+    gnutls_hash_deinit(digest_ctx, NULL);
 }
 
 int
diff --git a/src/coap_mbedtls.c b/src/coap_mbedtls.c
index a4f55659..0106b71e 100644
--- a/src/coap_mbedtls.c
+++ b/src/coap_mbedtls.c
@@ -2880,8 +2880,10 @@ coap_digest_setup(void) {
 
 void
 coap_digest_free(coap_digest_ctx_t *digest_ctx) {
-  mbedtls_sha256_free(digest_ctx);
-  mbedtls_free(digest_ctx);
+  if (digest_ctx) {
+    mbedtls_sha256_free(digest_ctx);
+    mbedtls_free(digest_ctx);
+  }
 }
 
 int
diff --git a/src/coap_openssl.c b/src/coap_openssl.c
index a8ed48eb..5e589e78 100644
--- a/src/coap_openssl.c
+++ b/src/coap_openssl.c
@@ -4082,7 +4082,8 @@ coap_digest_setup(void) {
 
 void
 coap_digest_free(coap_digest_ctx_t *digest_ctx) {
-  EVP_MD_CTX_free(digest_ctx);
+  if (digest_ctx)
+    EVP_MD_CTX_free(digest_ctx);
 }
 
 int
diff --git a/src/coap_wolfssl.c b/src/coap_wolfssl.c
index 4c2083a5..b3faa09d 100644
--- a/src/coap_wolfssl.c
+++ b/src/coap_wolfssl.c
@@ -2859,7 +2859,8 @@ coap_digest_setup(void) {
 
 void
 coap_digest_free(coap_digest_ctx_t *digest_ctx) {
-  wolfSSL_EVP_MD_CTX_free(digest_ctx);
+  if (digest_ctx)
+    wolfSSL_EVP_MD_CTX_free(digest_ctx);
 }
 
 int