diff --git a/ext/openssl/ossl_pkey.c b/ext/openssl/ossl_pkey.c
index ba8c507d3..7539e05a2 100644
--- a/ext/openssl/ossl_pkey.c
+++ b/ext/openssl/ossl_pkey.c
@@ -437,19 +437,20 @@ static const struct pkey_from_parameters_alias rsa_aliases[] = {
     { "q",    OSSL_PKEY_PARAM_RSA_FACTOR2 },
     { "dmp1", OSSL_PKEY_PARAM_RSA_EXPONENT1 },
     { "dmq1", OSSL_PKEY_PARAM_RSA_EXPONENT2 },
-    { "iqmp", OSSL_PKEY_PARAM_RSA_COEFFICIENT1 }
+    { "iqmp", OSSL_PKEY_PARAM_RSA_COEFFICIENT1 },
+    { "", "" }
 };
 
 static const struct pkey_from_parameters_alias fcc_aliases[] = {
     { "pub_key",  OSSL_PKEY_PARAM_PUB_KEY },
-    { "priv_key", OSSL_PKEY_PARAM_PRIV_KEY }
+    { "priv_key", OSSL_PKEY_PARAM_PRIV_KEY },
+    { "", "" }
 };
 
 struct pkey_from_parameters_arg {
     OSSL_PARAM_BLD *param_bld;
     const OSSL_PARAM *settable_params;
     const struct pkey_from_parameters_alias *aliases;
-    size_t nAliases;
 };
 
 static int
@@ -463,7 +464,7 @@ add_parameter_to_builder(VALUE key, VALUE value, VALUE arg) {
     const char *key_ptr = StringValueCStr(key);
     const struct pkey_from_parameters_arg *params = (const struct pkey_from_parameters_arg *) arg;
 
-    for(size_t i = 0; i < params->nAliases; i++) {
+    for(int i = 0; strlen(params->aliases[i].alias) > 0; i++) {
         if(strcmp(params->aliases[i].alias, key_ptr) == 0) {
             key_ptr = params->aliases[i].param_name;
             break;
@@ -517,7 +518,7 @@ add_parameter_to_builder(VALUE key, VALUE value, VALUE arg) {
         cur += snprintf(cur, end-cur, fmt, settable_params->key);
     }
 
-    for(size_t i = 0; i < params->nAliases; i++) {
+    for(int i = 0; strlen(params->aliases[i].alias) > 0; i++) {
         const char *fmt = cur == message_buffer ? "%s" : ", %s";
         if (cur > end)
             break;
@@ -556,13 +557,10 @@ pkey_from_parameters(int argc, VALUE *argv, VALUE self)
         ossl_raise(ePKeyError, "EVP_PKEY_fromdata_settable");
     }
 
-    if (strcmp("RSA", algorithm) == 0) {
+    if (strcmp("RSA", algorithm) == 0)
         from_params_args.aliases = rsa_aliases;
-        from_params_args.nAliases = sizeof(rsa_aliases)/sizeof((rsa_aliases)[0]);
-    } else {
+    else
         from_params_args.aliases = fcc_aliases;
-        from_params_args.nAliases = sizeof(fcc_aliases)/sizeof((fcc_aliases)[0]);
-    }
 
     rb_hash_foreach(options, &add_parameter_to_builder, (VALUE) &from_params_args);