diff --git a/ext/random/engine_pcgoneseq128xslrr64.c b/ext/random/engine_pcgoneseq128xslrr64.c
index ccbe146321e..b19aff7e987 100644
--- a/ext/random/engine_pcgoneseq128xslrr64.c
+++ b/ext/random/engine_pcgoneseq128xslrr64.c
@@ -153,7 +153,7 @@ PHP_METHOD(Random_Engine_PcgOneseq128XslRr64, __construct)
 	ZEND_PARSE_PARAMETERS_END();
 
 	if (seed_is_null) {
-		if (php_random_bytes_throw(&state->state, sizeof(php_random_uint128_t)) == FAILURE) {
+		if (php_random_bytes_throw(&state->state, sizeof(state->state)) == FAILURE) {
 			zend_throw_exception(random_ce_Random_RandomException, "Failed to generate a random seed", 0);
 			RETURN_THROWS();
 		}
diff --git a/ext/random/engine_xoshiro256starstar.c b/ext/random/engine_xoshiro256starstar.c
index 78cafe341c3..5d4dad08a14 100644
--- a/ext/random/engine_xoshiro256starstar.c
+++ b/ext/random/engine_xoshiro256starstar.c
@@ -213,7 +213,7 @@ PHP_METHOD(Random_Engine_Xoshiro256StarStar, __construct)
 
 	if (seed_is_null) {
 		do {
-			if (php_random_bytes_throw(&state->state, 32) == FAILURE) {
+			if (php_random_bytes_throw(&state->state, sizeof(state->state)) == FAILURE) {
 				zend_throw_exception(random_ce_Random_RandomException, "Failed to generate a random seed", 0);
 				RETURN_THROWS();
 			}