diff --git a/ext/dom/element.c b/ext/dom/element.c
index cf1a762768a8..797f215e173d 100644
--- a/ext/dom/element.c
+++ b/ext/dom/element.c
@@ -1210,19 +1210,17 @@ Since: DOM Level 2
 */
 PHP_METHOD(DOMElement, getAttributeNodeNS)
 {
-	zval *id;
 	xmlNodePtr elemp;
 	xmlAttrPtr attrp;
 	dom_object *intern;
 	size_t uri_len, name_len;
 	char *uri, *name;
 
-	id = ZEND_THIS;
 	if (zend_parse_parameters(ZEND_NUM_ARGS(), "s!s", &uri, &uri_len, &name, &name_len) == FAILURE) {
 		RETURN_THROWS();
 	}
 
-	DOM_GET_OBJ(elemp, id, xmlNodePtr, intern);
+	DOM_GET_OBJ(elemp, ZEND_THIS, xmlNodePtr, intern);
 
 	bool follow_spec = php_dom_follow_spec_intern(intern);
 	if (follow_spec && uri_len == 0) {
@@ -1239,16 +1237,11 @@ PHP_METHOD(DOMElement, getAttributeNodeNS)
 				/* Keep parent alive, because we're a fake child. */
 				GC_ADDREF(&intern->std);
 				(void) php_dom_create_fake_namespace_decl(elemp, nsptr, return_value, intern);
-			} else {
-				RETURN_NULL();
 			}
-		} else {
-			RETURN_NULL();
 		}
 	} else {
 		DOM_RET_OBJ((xmlNodePtr) attrp, intern);
 	}
-
 }
 /* }}} end dom_element_get_attribute_node_ns */
 
diff --git a/ext/dom/node.c b/ext/dom/node.c
index 40aaf2766926..debc08c4958c 100644
--- a/ext/dom/node.c
+++ b/ext/dom/node.c
@@ -1878,8 +1878,7 @@ static void dom_node_lookup_prefix(INTERNAL_FUNCTION_PARAMETERS, bool modern)
 			case XML_DOCUMENT_FRAG_NODE:
 			case XML_DOCUMENT_TYPE_NODE:
 			case XML_DTD_NODE:
-				RETURN_NULL();
-				break;
+				return;
 			default:
 				lookupp = nodep->parent;
 		}
@@ -1898,8 +1897,6 @@ static void dom_node_lookup_prefix(INTERNAL_FUNCTION_PARAMETERS, bool modern)
 			}
 		}
 	}
-
-	RETURN_NULL();
 }
 
 PHP_METHOD(DOMNode, lookupPrefix)
@@ -2065,16 +2062,14 @@ PHP_METHOD(DOMNode, lookupNamespaceURI)
 			prefix = NULL;
 		}
 		const char *ns_uri = dom_locate_a_namespace(nodep, prefix);
-		if (ns_uri == NULL) {
-			RETURN_NULL();
-		} else {
+		if (ns_uri != NULL) {
 			RETURN_STRING(ns_uri);
 		}
 	} else {
 		if (nodep->type == XML_DOCUMENT_NODE || nodep->type == XML_HTML_DOCUMENT_NODE) {
 			nodep = xmlDocGetRootElement((xmlDocPtr) nodep);
 			if (nodep == NULL) {
-				RETURN_NULL();
+				return;
 			}
 		}
 
@@ -2083,8 +2078,6 @@ PHP_METHOD(DOMNode, lookupNamespaceURI)
 			RETURN_STRING((char *) nsptr->href);
 		}
 	}
-
-	RETURN_NULL();
 }
 /* }}} end dom_node_lookup_namespace_uri */
 
@@ -2294,13 +2287,12 @@ static void dom_node_get_node_path(INTERNAL_FUNCTION_PARAMETERS, bool throw)
 	zval *id;
 	xmlNode *nodep;
 	dom_object *intern;
-	char *value;
 
 	ZEND_PARSE_PARAMETERS_NONE();
 
 	DOM_GET_THIS_OBJ(nodep, id, xmlNodePtr, intern);
 
-	value = (char *) xmlGetNodePath(nodep);
+	char *value = (char *) xmlGetNodePath(nodep);
 	if (value == NULL) {
 		/* This is only possible when an invalid argument is passed (e.g. namespace declaration, but that's not the case for this call site),
 		 * or on allocation failure. So in other words, this only happens on allocation failure. */
@@ -2308,7 +2300,6 @@ static void dom_node_get_node_path(INTERNAL_FUNCTION_PARAMETERS, bool throw)
 			php_dom_throw_error(INVALID_STATE_ERR, /* strict */ true);
 			RETURN_THROWS();
 		}
-		RETURN_NULL();
 	} else {
 		RETVAL_STRING(value);
 		xmlFree(value);
diff --git a/ext/phar/phar.c b/ext/phar/phar.c
index b7becf27e32d..51b28ec2b749 100644
--- a/ext/phar/phar.c
+++ b/ext/phar/phar.c
@@ -1719,7 +1719,7 @@ static zend_result phar_open_from_fp(php_stream* fp, char *fname, size_t fname_l
 			}
 
 			if (got >= 512) {
-				if (phar_is_tar((char *) pos, fname)) { /* TODO: fix const correctness */
+				if (phar_is_tar(pos, fname)) {
 					php_stream_rewind(fp);
 					return phar_parse_tarfile(fp, fname, fname_len, alias, alias_len, pphar, compression, error);
 				}
diff --git a/ext/phar/phar_internal.h b/ext/phar/phar_internal.h
index bd3d7158c8e8..5acb0873ebdb 100644
--- a/ext/phar/phar_internal.h
+++ b/ext/phar/phar_internal.h
@@ -443,7 +443,7 @@ zend_result phar_open_archive_fp(phar_archive_data *phar);
 zend_result phar_copy_on_write(phar_archive_data **pphar);
 
 /* tar functions in tar.c */
-bool phar_is_tar(char *buf, char *fname);
+bool phar_is_tar(const char *buf, const char *fname);
 zend_result phar_parse_tarfile(php_stream* fp, char *fname, size_t fname_len, char *alias, size_t alias_len, phar_archive_data** pphar, uint32_t compression, char **error);
 ZEND_ATTRIBUTE_NONNULL_ARGS(1, 7, 8) zend_result phar_open_or_create_tar(char *fname, size_t fname_len, char *alias, size_t alias_len, bool is_data, uint32_t options, phar_archive_data** pphar, char **error);
 ZEND_ATTRIBUTE_NONNULL_ARGS(1, 4) void phar_tar_flush(phar_archive_data *phar, zend_string *user_stub, bool is_default_stub, char **error);
diff --git a/ext/phar/tar.c b/ext/phar/tar.c
index 4847597cce2e..67994289d0a9 100644
--- a/ext/phar/tar.c
+++ b/ext/phar/tar.c
@@ -87,10 +87,10 @@ static zend_result phar_tar_octal(char *buf, uint32_t val, size_t len) /* {{{ */
 }
 /* }}} */
 
-static uint32_t phar_tar_checksum(char *buf, size_t len) /* {{{ */
+static uint32_t phar_tar_checksum(const char *buf, size_t len) /* {{{ */
 {
 	uint32_t sum = 0;
-	char *end = buf + len;
+	const char *end = buf + len;
 
 	while (buf != end) {
 		sum += (unsigned char)*buf;
@@ -100,7 +100,7 @@ static uint32_t phar_tar_checksum(char *buf, size_t len) /* {{{ */
 }
 /* }}} */
 
-bool phar_is_tar(char *buf, char *fname) /* {{{ */
+bool phar_is_tar(const char *buf, const char *fname) /* {{{ */
 {
 	tar_header *header = (tar_header *) buf;
 	uint32_t checksum = phar_tar_number(header->checksum, sizeof(header->checksum));
diff --git a/ext/simplexml/simplexml.c b/ext/simplexml/simplexml.c
index d3248bb81208..16a8aaa22fc3 100644
--- a/ext/simplexml/simplexml.c
+++ b/ext/simplexml/simplexml.c
@@ -1413,14 +1413,10 @@ PHP_METHOD(SimpleXMLElement, asXML)
 
 static inline void sxe_add_namespace_name_raw(zval *return_value, const char *prefix, const char *href)
 {
-	zend_string *key = zend_string_init(prefix, strlen(prefix), 0);
-	zval zv;
-
-	if (!zend_hash_exists(Z_ARRVAL_P(return_value), key)) {
-		ZVAL_STRING(&zv, href);
-		zend_hash_add_new(Z_ARRVAL_P(return_value), key, &zv);
+	zval *zv = zend_hash_str_lookup(Z_ARRVAL_P(return_value), prefix, strlen(prefix));
+	if (Z_ISNULL_P(zv)) {
+		ZVAL_STRING(zv, href);
 	}
-	zend_string_release_ex(key, 0);
 }
 
 static inline void sxe_add_namespace_name(zval *return_value, xmlNsPtr ns) /* {{{ */
diff --git a/main/main.c b/main/main.c
index 48022cddfc8d..f190eab3d094 100644
--- a/main/main.c
+++ b/main/main.c
@@ -351,6 +351,7 @@ static PHP_INI_MH(OnChangeMemoryLimit)
 
 		zend_ini_entry *max_mem_limit_ini = zend_hash_str_find_ptr(EG(ini_directives), ZEND_STRL("max_memory_limit"));
 		entry->value = zend_string_init(ZSTR_VAL(max_mem_limit_ini->value), ZSTR_LEN(max_mem_limit_ini->value), true);
+		GC_MAKE_PERSISTENT_LOCAL(entry->value);
 		PG(memory_limit) = PG(max_memory_limit);
 
 		return SUCCESS;