diff --git a/ext/zlib/zlib.c b/ext/zlib/zlib.c
index e73e168708a..b0f21c45699 100644
--- a/ext/zlib/zlib.c
+++ b/ext/zlib/zlib.c
@@ -805,7 +805,7 @@ static bool zlib_create_dictionary_string(HashTable *options, char **dict, size_
 
 			case IS_ARRAY: {
 				HashTable *dictionary = Z_ARR_P(option_buffer);
-				bool result = 1;
+				bool result = true;
 
 				if (zend_hash_num_elements(dictionary) > 0) {
 					zend_string **strings = safe_emalloc(zend_hash_num_elements(dictionary), sizeof(zend_string *), 0);
@@ -815,18 +815,18 @@ static bool zlib_create_dictionary_string(HashTable *options, char **dict, size_
 					ZEND_HASH_FOREACH_VAL(dictionary, cur) {
 						zend_string *string = zval_try_get_string(cur);
 						if (string == NULL) {
-							result = 0;
+							result = false;
 							break;
 						}
 						*dictlen += ZSTR_LEN(string) + 1;
 						strings[total++] = string;
 						if (ZSTR_LEN(string) == 0) {
-							result = 0;
+							result = false;
 							zend_argument_value_error(2, "must not contain empty strings");
 							break;
 						}
 						if (zend_str_has_nul_byte(string)) {
-							result = 0;
+							result = false;
 							zend_argument_value_error(2, "must not contain strings with null bytes");
 							break;
 						}
diff --git a/ext/zlib/zlib_filter.c b/ext/zlib/zlib_filter.c
index 24d418ae04c..6da5ff2a595 100644
--- a/ext/zlib/zlib_filter.c
+++ b/ext/zlib/zlib_filter.c
@@ -238,7 +238,7 @@ static php_stream_filter_status_t php_zlib_deflate_filter(
 		status = Z_OK;
 		while (status == Z_OK) {
 			status = deflate(&(data->strm), (flags & PSFS_FLAG_FLUSH_CLOSE ? Z_FINISH : Z_SYNC_FLUSH));
-			data->finished = 1;
+			data->finished = true;
 			if (data->strm.avail_out < data->outbuf_len) {
 				size_t bucketlen = data->outbuf_len - data->strm.avail_out;
 
@@ -335,7 +335,7 @@ static php_stream_filter *php_zlib_filter_create(const char *filtername, zval *f
 		}
 
 		/* RFC 1951 Inflate */
-		data->finished = '\0';
+		data->finished = false;
 		status = inflateInit2(&(data->strm), windowBits);
 		fops = &php_zlib_inflate_ops;
 	} else if (strcasecmp(filtername, "zlib.deflate") == 0) {
@@ -399,7 +399,7 @@ factory_setlevel:
 			}
 		}
 		status = deflateInit2(&(data->strm), level, Z_DEFLATED, windowBits, memLevel, 0);
-		data->finished = 1;
+		data->finished = true;
 		fops = &php_zlib_deflate_ops;
 	} else {
 		status = Z_DATA_ERROR;