diff --git a/ext/random/engine_mt19937.c b/ext/random/engine_mt19937.c
index 7c9d1741d81f1..7b91c45648e92 100644
--- a/ext/random/engine_mt19937.c
+++ b/ext/random/engine_mt19937.c
@@ -127,7 +127,7 @@ static inline void mt19937_reload(php_random_status_state_mt19937 *state)
 
 PHPAPI inline void php_random_mt19937_seed32(php_random_status_state_mt19937 *state, uint32_t seed)
 {
-	uint32_t i, prev_state;
+	uint32_t i;
 
 	/* Initialize generator state with seed
 	   See Knuth TAOCP Vol 2, 3rd Ed, p.106 for multiplier.
@@ -135,7 +135,7 @@ PHPAPI inline void php_random_mt19937_seed32(php_random_status_state_mt19937 *st
 	   only MSBs of the state array.  Modified 9 Jan 2002 by Makoto Matsumoto. */
 	state->state[0] = seed;
 	for (i = 1; i < N; i++) {
-		prev_state = state->state[i - 1];
+		uint32_t prev_state = state->state[i - 1];
 		state->state[i] = (1812433253U * (prev_state  ^ (prev_state  >> 30)) + i) & 0xffffffffU;
 	}
 	state->count = i;
@@ -188,7 +188,7 @@ static bool serialize(void *state, HashTable *data)
 	return true;
 }
 
-static bool unserialize(void *state, HashTable *data)
+static bool unserialize(void *state, const HashTable *data)
 {
 	php_random_status_state_mt19937 *s = state;
 	zval *t;
diff --git a/ext/random/engine_pcgoneseq128xslrr64.c b/ext/random/engine_pcgoneseq128xslrr64.c
index 9ff4f911920b2..ffb6385540f10 100644
--- a/ext/random/engine_pcgoneseq128xslrr64.c
+++ b/ext/random/engine_pcgoneseq128xslrr64.c
@@ -80,11 +80,10 @@ static bool serialize(void *state, HashTable *data)
 	return true;
 }
 
-static bool unserialize(void *state, HashTable *data)
+static bool unserialize(void *state, const HashTable *data)
 {
 	php_random_status_state_pcgoneseq128xslrr64 *s = state;
 	uint64_t u[2];
-	zval *t;
 
 	/* Verify the expected number of elements, this implicitly ensures that no additional elements are present. */
 	if (zend_hash_num_elements(data) != 2) {
@@ -92,7 +91,7 @@ static bool unserialize(void *state, HashTable *data)
 	}
 
 	for (uint32_t i = 0; i < 2; i++) {
-		t = zend_hash_index_find(data, i);
+		zval *t = zend_hash_index_find(data, i);
 		if (!t || Z_TYPE_P(t) != IS_STRING || Z_STRLEN_P(t) != (2 * sizeof(uint64_t))) {
 			return false;
 		}
diff --git a/ext/random/engine_xoshiro256starstar.c b/ext/random/engine_xoshiro256starstar.c
index 1a054362f0652..d46ecda97e713 100644
--- a/ext/random/engine_xoshiro256starstar.c
+++ b/ext/random/engine_xoshiro256starstar.c
@@ -131,10 +131,9 @@ static bool serialize(void *state, HashTable *data)
 	return true;
 }
 
-static bool unserialize(void *state, HashTable *data)
+static bool unserialize(void *state, const HashTable *data)
 {
 	php_random_status_state_xoshiro256starstar *s = state;
-	zval *t;
 
 	/* Verify the expected number of elements, this implicitly ensures that no additional elements are present. */
 	if (zend_hash_num_elements(data) != 4) {
@@ -142,7 +141,7 @@ static bool unserialize(void *state, HashTable *data)
 	}
 
 	for (uint32_t i = 0; i < 4; i++) {
-		t = zend_hash_index_find(data, i);
+		zval *t = zend_hash_index_find(data, i);
 		if (!t || Z_TYPE_P(t) != IS_STRING || Z_STRLEN_P(t) != (2 * sizeof(uint64_t))) {
 			return false;
 		}
diff --git a/ext/random/random.c b/ext/random/random.c
index 46a6c4fd44f2c..1a0b520c141bf 100644
--- a/ext/random/random.c
+++ b/ext/random/random.c
@@ -240,7 +240,7 @@ PHPAPI void *php_random_status_alloc(const php_random_algo *algo, const bool per
 	return algo->state_size > 0 ? pecalloc(1, algo->state_size, persistent) : NULL;
 }
 
-PHPAPI void *php_random_status_copy(const php_random_algo *algo, void *old_status, void *new_status)
+PHPAPI void *php_random_status_copy(const php_random_algo *algo, const void *old_status, void *new_status)
 {
 	return memcpy(new_status, old_status, algo->state_size);
 }
@@ -250,7 +250,7 @@ PHPAPI void php_random_status_free(void *status, const bool persistent)
 	pefree(status, persistent);
 }
 
-PHPAPI php_random_engine *php_random_engine_common_init(zend_class_entry *ce, zend_object_handlers *handlers, const php_random_algo *algo)
+PHPAPI php_random_engine *php_random_engine_common_init(zend_class_entry *ce, const zend_object_handlers *handlers, const php_random_algo *algo)
 {
 	php_random_engine *engine = zend_object_alloc(sizeof(php_random_engine), ce);
 
@@ -355,12 +355,13 @@ PHPAPI zend_string *php_random_bin2hex_le(const void *ptr, const size_t len)
 
 /* {{{ php_random_hex2bin_le */
 /* stolen from standard/string.c */
-PHPAPI bool php_random_hex2bin_le(zend_string *hexstr, void *dest)
+PHPAPI bool php_random_hex2bin_le(const zend_string *hexstr, void *dest)
 {
 	size_t len = hexstr->len >> 1;
-	unsigned char *str = (unsigned char *) hexstr->val, c, l, d;
+	const unsigned char *str = (unsigned char *) ZSTR_VAL(hexstr);
+	unsigned char c, l, d;
 	unsigned char *ptr = (unsigned char *) dest;
-	int is_letter, i = 0;
+	uint32_t is_letter, i = 0;
 
 #ifdef WORDS_BIGENDIAN
 	/* force little endian */
@@ -462,7 +463,7 @@ PHPAPI zend_long php_mt_rand_range(zend_long min, zend_long max)
  * rand() allows min > max, mt_rand does not */
 PHPAPI zend_long php_mt_rand_common(zend_long min, zend_long max)
 {
-	php_random_status_state_mt19937 *s = php_random_default_status();
+	const php_random_status_state_mt19937 *s = php_random_default_status();
 
 	if (s->mode == MT_RAND_MT19937) {
 		return php_mt_rand_range(min, max);
@@ -524,9 +525,8 @@ PHP_FUNCTION(mt_srand)
 PHP_FUNCTION(mt_rand)
 {
 	zend_long min, max;
-	int argc = ZEND_NUM_ARGS();
 
-	if (argc == 0) {
+	if (ZEND_NUM_ARGS() == 0) {
 		/* genrand_int31 in mt19937ar.c performs a right shift */
 		RETURN_LONG(php_mt_rand() >> 1);
 	}
@@ -562,9 +562,8 @@ PHP_FUNCTION(mt_getrandmax)
 PHP_FUNCTION(rand)
 {
 	zend_long min, max;
-	int argc = ZEND_NUM_ARGS();
 
-	if (argc == 0) {
+	if (ZEND_NUM_ARGS() == 0) {
 		/* genrand_int31 in mt19937ar.c performs a right shift */
 		RETURN_LONG(php_mt_rand() >> 1);
 	}
@@ -633,7 +632,7 @@ PHP_FUNCTION(random_int)
 }
 /* }}} */
 
-static inline void fallback_seed_add(PHP_SHA1_CTX *c, void *p, size_t l){
+static inline void fallback_seed_add(PHP_SHA1_CTX *c, const void *p, size_t l){
 	/* Wrapper around PHP_SHA1Update allowing to pass
 	 * arbitrary pointers without (unsigned char*) casts
 	 * everywhere.
diff --git a/ext/random/randomizer.c b/ext/random/randomizer.c
index 0585ea95e668e..19c21f620aa78 100644
--- a/ext/random/randomizer.c
+++ b/ext/random/randomizer.c
@@ -93,7 +93,7 @@ PHP_METHOD(Random_Randomizer, __construct)
 /* {{{ Generate a float in [0, 1) */
 PHP_METHOD(Random_Randomizer, nextFloat)
 {
-	php_random_randomizer *randomizer = Z_RANDOM_RANDOMIZER_P(ZEND_THIS);
+	const php_random_randomizer *randomizer = Z_RANDOM_RANDOMIZER_P(ZEND_THIS);
 	php_random_algo_with_state engine = randomizer->engine;
 
 	uint64_t result;
@@ -136,7 +136,7 @@ PHP_METHOD(Random_Randomizer, nextFloat)
  */
 PHP_METHOD(Random_Randomizer, getFloat)
 {
-	php_random_randomizer *randomizer = Z_RANDOM_RANDOMIZER_P(ZEND_THIS);
+	const php_random_randomizer *randomizer = Z_RANDOM_RANDOMIZER_P(ZEND_THIS);
 	double min, max;
 	zend_object *bounds = NULL;
 	int bounds_type = 'C' + sizeof("ClosedOpen") - 1;
@@ -159,8 +159,8 @@ PHP_METHOD(Random_Randomizer, getFloat)
 	}
 
 	if (bounds) {
-		zval *case_name = zend_enum_fetch_case_name(bounds);
-		zend_string *bounds_name = Z_STR_P(case_name);
+		const zval *case_name = zend_enum_fetch_case_name(bounds);
+		const zend_string *bounds_name = Z_STR_P(case_name);
 
 		bounds_type = ZSTR_VAL(bounds_name)[0] + ZSTR_LEN(bounds_name);
 	}
@@ -210,7 +210,7 @@ PHP_METHOD(Random_Randomizer, getFloat)
 /* {{{ Generate positive random number */
 PHP_METHOD(Random_Randomizer, nextInt)
 {
-	php_random_randomizer *randomizer = Z_RANDOM_RANDOMIZER_P(ZEND_THIS);
+	const php_random_randomizer *randomizer = Z_RANDOM_RANDOMIZER_P(ZEND_THIS);
 	php_random_algo_with_state engine = randomizer->engine;
 
 	ZEND_PARSE_PARAMETERS_NONE();
@@ -231,7 +231,7 @@ PHP_METHOD(Random_Randomizer, nextInt)
 /* {{{ Generate random number in range */
 PHP_METHOD(Random_Randomizer, getInt)
 {
-	php_random_randomizer *randomizer = Z_RANDOM_RANDOMIZER_P(ZEND_THIS);
+	const php_random_randomizer *randomizer = Z_RANDOM_RANDOMIZER_P(ZEND_THIS);
 	php_random_algo_with_state engine = randomizer->engine;
 
 	uint64_t result;
@@ -274,7 +274,7 @@ PHP_METHOD(Random_Randomizer, getInt)
 /* {{{ Generate random bytes string in ordered length */
 PHP_METHOD(Random_Randomizer, getBytes)
 {
-	php_random_randomizer *randomizer = Z_RANDOM_RANDOMIZER_P(ZEND_THIS);
+	const php_random_randomizer *randomizer = Z_RANDOM_RANDOMIZER_P(ZEND_THIS);
 	php_random_algo_with_state engine = randomizer->engine;
 
 	zend_string *retval;
@@ -330,7 +330,7 @@ PHP_METHOD(Random_Randomizer, getBytes)
 			RETURN_THROWS();
 		}
 
- non_64:
+non_64:
 
 		for (size_t i = 0; i < result.size; i++) {
 			ZSTR_VAL(retval)[total_size++] = result.result & 0xff;
@@ -349,7 +349,7 @@ PHP_METHOD(Random_Randomizer, getBytes)
 /* {{{ Shuffling array */
 PHP_METHOD(Random_Randomizer, shuffleArray)
 {
-	php_random_randomizer *randomizer = Z_RANDOM_RANDOMIZER_P(ZEND_THIS);
+	const php_random_randomizer *randomizer = Z_RANDOM_RANDOMIZER_P(ZEND_THIS);
 	zval *array;
 
 	ZEND_PARSE_PARAMETERS_START(1, 1)
@@ -366,7 +366,7 @@ PHP_METHOD(Random_Randomizer, shuffleArray)
 /* {{{ Shuffling binary */
 PHP_METHOD(Random_Randomizer, shuffleBytes)
 {
-	php_random_randomizer *randomizer = Z_RANDOM_RANDOMIZER_P(ZEND_THIS);
+	const php_random_randomizer *randomizer = Z_RANDOM_RANDOMIZER_P(ZEND_THIS);
 	zend_string *bytes;
 
 	ZEND_PARSE_PARAMETERS_START(1, 1)
@@ -387,8 +387,8 @@ PHP_METHOD(Random_Randomizer, shuffleBytes)
 /* {{{ Pick keys */
 PHP_METHOD(Random_Randomizer, pickArrayKeys)
 {
-	php_random_randomizer *randomizer = Z_RANDOM_RANDOMIZER_P(ZEND_THIS);
-	zval *input, t;
+	const php_random_randomizer *randomizer = Z_RANDOM_RANDOMIZER_P(ZEND_THIS);
+	zval *input;
 	zend_long num_req;
 
 	ZEND_PARSE_PARAMETERS_START(2, 2);
@@ -408,6 +408,7 @@ PHP_METHOD(Random_Randomizer, pickArrayKeys)
 
 	/* Keep compatibility, But the result is always an array */
 	if (Z_TYPE_P(return_value) != IS_ARRAY) {
+		zval t;
 		ZVAL_COPY_VALUE(&t, return_value);
 		array_init(return_value);
 		zend_hash_next_index_insert(Z_ARRVAL_P(return_value), &t);
@@ -418,7 +419,7 @@ PHP_METHOD(Random_Randomizer, pickArrayKeys)
 /* {{{ Get Random Bytes for String */
 PHP_METHOD(Random_Randomizer, getBytesFromString)
 {
-	php_random_randomizer *randomizer = Z_RANDOM_RANDOMIZER_P(ZEND_THIS);
+	const php_random_randomizer *randomizer = Z_RANDOM_RANDOMIZER_P(ZEND_THIS);
 	php_random_algo_with_state engine = randomizer->engine;
 
 	zend_long user_length;