diff --git a/src/libsodium/crypto_pwhash/scryptsalsa208sha256/crypto_scrypt-common.c b/src/libsodium/crypto_pwhash/scryptsalsa208sha256/crypto_scrypt-common.c
index ae5e4b84..01a1e094 100644
--- a/src/libsodium/crypto_pwhash/scryptsalsa208sha256/crypto_scrypt-common.c
+++ b/src/libsodium/crypto_pwhash/scryptsalsa208sha256/crypto_scrypt-common.c
@@ -60,7 +60,7 @@ encode64(uint8_t * dst, size_t dstlen, const uint8_t * src, size_t srclen)
         } while (bits < 24 && i < srclen);
         dnext = encode64_uint32(dst, dstlen, value, bits);
         if (!dnext) {
-            return NULL;
+            return NULL; /* LCOV_EXCL_LINE */
         }
         dstlen -= dnext - dst;
         dst = dnext;
diff --git a/test/default/pwhash.c b/test/default/pwhash.c
index b5006d65..1c07f271 100644
--- a/test/default/pwhash.c
+++ b/test/default/pwhash.c
@@ -204,6 +204,9 @@ static void tv3(void)
           { "Y0!?iQa9M%5ekffW(`",
             "$7$A6....1....TrXs5Zk6s8sWHpQgWDIXTR8kUU3s6Jc3s.DtdS8M2i4$"
             "a4ik5hGDN7foMuHOW.cp.CtX01UyCeO0.JAG.AHPpx5" },
+
+          /* Invalid pwhash strings */
+
           { "Y0!?iQa9M%5ekffW(`",
             "$7$A6....1....$TrXs5Zk6s8sWHpQgWDIXTR8kUU3s6Jc3s.DtdS8M2i4"
             "a4ik5hGDN7foMuHOW.cp.CtX01UyCeO0.JAG.AHPpx5" },