diff --git a/src/libsodium/crypto_hash/sha512/cp/hash_sha512_cp.c b/src/libsodium/crypto_hash/sha512/cp/hash_sha512_cp.c
index 3778dfe3..8d0f2536 100644
--- a/src/libsodium/crypto_hash/sha512/cp/hash_sha512_cp.c
+++ b/src/libsodium/crypto_hash/sha512/cp/hash_sha512_cp.c
@@ -222,9 +222,11 @@ crypto_hash_sha512_update(crypto_hash_sha512_state *state,
 
     bitlen[1] = ((uint64_t) inlen) << 3;
     bitlen[0] = ((uint64_t) inlen) >> 61;
+    /* LCOV_EXCL_START */
     if ((state->count[1] += bitlen[1]) < bitlen[1]) {
         state->count[0]++;
     }
+    /* LCOV_EXCL_STOP */
     state->count[0] += bitlen[0];
     if (inlen < 128 - r) {
         for (i = 0; i < inlen; i++) {
diff --git a/src/libsodium/crypto_pwhash/argon2/argon2-core.c b/src/libsodium/crypto_pwhash/argon2/argon2-core.c
index 091ce33f..85846b78 100644
--- a/src/libsodium/crypto_pwhash/argon2/argon2-core.c
+++ b/src/libsodium/crypto_pwhash/argon2/argon2-core.c
@@ -154,12 +154,12 @@ static void clear_memory(argon2_instance_t *instance, int clear);
 static void
 clear_memory(argon2_instance_t *instance, int clear)
 {
+    /* LCOV_EXCL_START */
     if (instance->region != NULL && clear) {
-        /* LCOV_EXCL_START */
         sodium_memzero(instance->region->memory,
                        sizeof(block) * instance->memory_blocks);
-        /* LCOV_EXCL_STOP */
     }
+    /* LCOV_EXCL_STOP */
 }
 
 /* Deallocates memory
@@ -510,10 +510,12 @@ initial_hash(uint8_t *blockhash, argon2_context *context, argon2_type type)
         crypto_generichash_blake2b_update(
             &BlakeHash, (const uint8_t *) context->pwd, context->pwdlen);
 
+        /* LCOV_EXCL_START */
         if (context->flags & ARGON2_FLAG_CLEAR_PASSWORD) {
-            sodium_memzero(context->pwd, context->pwdlen); /* LCOV_EXCL_LINE */
-            context->pwdlen = 0;                           /* LCOV_EXCL_LINE */
+            sodium_memzero(context->pwd, context->pwdlen);
+            context->pwdlen = 0;
         }
+        /* LCOV_EXCL_STOP */
     }
 
     STORE32_LE(value, context->saltlen);
@@ -527,8 +529,8 @@ initial_hash(uint8_t *blockhash, argon2_context *context, argon2_type type)
     STORE32_LE(value, context->secretlen);
     crypto_generichash_blake2b_update(&BlakeHash, value, sizeof(value));
 
+    /* LCOV_EXCL_START */
     if (context->secret != NULL) {
-        /* LCOV_EXCL_START */
         crypto_generichash_blake2b_update(
             &BlakeHash, (const uint8_t *) context->secret, context->secretlen);
 
@@ -536,18 +538,18 @@ initial_hash(uint8_t *blockhash, argon2_context *context, argon2_type type)
             sodium_memzero(context->secret, context->secretlen);
             context->secretlen = 0;
         }
-        /* LCOV_EXCL_STOP */
     }
+    /* LCOV_EXCL_STOP */
 
     STORE32_LE(value, context->adlen);
     crypto_generichash_blake2b_update(&BlakeHash, value, sizeof(value));
 
+    /* LCOV_EXCL_START */    
     if (context->ad != NULL) {
-        /* LCOV_EXCL_START */
         crypto_generichash_blake2b_update(
             &BlakeHash, (const uint8_t *) context->ad, context->adlen);
-        /* LCOV_EXCL_STOP */
     }
+    /* LCOV_EXCL_STOP */
 
     crypto_generichash_blake2b_final(&BlakeHash, blockhash,
                                      ARGON2_PREHASH_DIGEST_LENGTH);
diff --git a/test/default/box2.c b/test/default/box2.c
index b0174d47..3e46fda8 100644
--- a/test/default/box2.c
+++ b/test/default/box2.c
@@ -64,6 +64,8 @@ main(void)
     assert(ret == -1);
 
     memset(m, 0, sizeof m);
+    ret = crypto_box_beforenm(k, small_order_p, bobsk);
+    assert(ret == -1);
     ret = crypto_box_beforenm(k, alicepk, bobsk);
     assert(ret == 0);
     if (crypto_box_open_afternm(m, c, 163, nonce, k) == 0) {
diff --git a/test/default/misuse.c b/test/default/misuse.c
index 0a08cd91..d8564625 100644
--- a/test/default/misuse.c
+++ b/test/default/misuse.c
@@ -5,12 +5,22 @@
 #include <signal.h>
 
 static void
-sigabrt_handler_5(int sig)
+sigabrt_handler_6(int sig)
 {
     (void) sig;
     exit(0);
 }
 
+static void
+sigabrt_handler_5(int sig)
+{
+    (void) sig;
+    signal(SIGABRT, sigabrt_handler_6);
+    assert(crypto_aead_xchacha20poly1305_ietf_encrypt(NULL, NULL, NULL, UINT64_MAX,
+                                                      NULL, 0, NULL, NULL, NULL) == -1);
+    exit(1);
+}
+
 static void
 sigabrt_handler_4(int sig)
 {
diff --git a/test/default/xchacha20.c b/test/default/xchacha20.c
index 0074e827..cbb12a0b 100644
--- a/test/default/xchacha20.c
+++ b/test/default/xchacha20.c
@@ -164,6 +164,11 @@ tv_stream_xchacha20(void)
     hex = (char *) sodium_malloc(192 * 2 + 1);
     sodium_bin2hex(hex, 192 * 2 + 1, out, 192);
     printf("%s\n", hex);
+
+    memset(key, 0, crypto_stream_xchacha20_KEYBYTES);
+    crypto_stream_xchacha20_keygen(key);
+    assert(sodium_is_zero(key, crypto_stream_xchacha20_KEYBYTES) == 0);
+
     sodium_free(hex);
     sodium_free(out);
     sodium_free(out2);
@@ -234,6 +239,12 @@ tv_secretbox_xchacha20poly1305(void)
         assert(memcmp(out, out2,
                       crypto_secretbox_xchacha20poly1305_MACBYTES + m_len) == 0);
         n = randombytes_uniform(crypto_secretbox_xchacha20poly1305_MACBYTES + m_len);
+        assert(crypto_secretbox_xchacha20poly1305_open_easy
+               (out2, out2, crypto_secretbox_xchacha20poly1305_MACBYTES - 1,
+                nonce, key) == -1);
+        assert(crypto_secretbox_xchacha20poly1305_open_easy
+               (out2, out2, 0,
+                nonce, key) == -1);
         out2[n]++;
         assert(crypto_secretbox_xchacha20poly1305_open_easy
                (out2, out2, crypto_secretbox_xchacha20poly1305_MACBYTES + m_len,
@@ -326,6 +337,12 @@ tv_box_xchacha20poly1305(void)
                (out, m, SIZE_MAX, nonce, pc) == -1);
         assert(crypto_box_curve25519xchacha20poly1305_easy_afternm
                (out, m, m_len, nonce, pc) == 0);
+        assert(crypto_box_curve25519xchacha20poly1305_open_easy_afternm
+               (m2, out, crypto_box_curve25519xchacha20poly1305_MACBYTES - 1,
+                nonce, pc) == -1);
+        assert(crypto_box_curve25519xchacha20poly1305_open_easy_afternm
+               (m2, out, 0,
+                nonce, pc) == -1);
         assert(crypto_box_curve25519xchacha20poly1305_open_easy_afternm
                (m2, out, crypto_box_curve25519xchacha20poly1305_MACBYTES + m_len,
                 nonce, pc) == 0);