diff --git a/include/aws/common/uri.h b/include/aws/common/uri.h
index edc3fb2bd..137ba7df8 100644
--- a/include/aws/common/uri.h
+++ b/include/aws/common/uri.h
@@ -23,7 +23,7 @@ struct aws_uri {
     struct aws_byte_cursor user;
     struct aws_byte_cursor password;
     struct aws_byte_cursor host_name;
-    uint16_t port;
+    uint32_t port;
     struct aws_byte_cursor path;
     struct aws_byte_cursor query_string;
     struct aws_byte_cursor path_and_query;
@@ -49,7 +49,7 @@ struct aws_uri_builder_options {
     struct aws_byte_cursor scheme;
     struct aws_byte_cursor path;
     struct aws_byte_cursor host_name;
-    uint16_t port;
+    uint32_t port;
     struct aws_array_list *query_params;
     struct aws_byte_cursor query_string;
 };
@@ -107,7 +107,7 @@ AWS_COMMON_API const struct aws_byte_cursor *aws_uri_host_name(const struct aws_
  * Returns the port portion of the authority if it was present, otherwise, returns 0.
  * If this is 0, it is the users job to determine the correct port based on scheme and protocol.
  */
-AWS_COMMON_API uint16_t aws_uri_port(const struct aws_uri *uri);
+AWS_COMMON_API uint32_t aws_uri_port(const struct aws_uri *uri);
 
 /**
  * Returns the path and query portion of the uri (i.e., the thing you send across the wire).
diff --git a/source/uri.c b/source/uri.c
index 9e6920488..f9ecc9d77 100644
--- a/source/uri.c
+++ b/source/uri.c
@@ -30,6 +30,9 @@ struct uri_parser {
     enum parser_state state;
 };
 
+/* strlen of UINT32_MAX "4294967295" is 10, plus 1 for '\0' */
+#define PORT_BUFFER_SIZE 11
+
 typedef void(parse_fn)(struct uri_parser *parser, struct aws_byte_cursor *str);
 
 static void s_parse_scheme(struct uri_parser *parser, struct aws_byte_cursor *str);
@@ -101,8 +104,7 @@ int aws_uri_init_from_builder_options(
     buffer_size += options->host_name.len;
 
     if (options->port) {
-        /* max strlen of a 16 bit integer is 5 */
-        buffer_size += 6;
+        buffer_size += PORT_BUFFER_SIZE;
     }
 
     buffer_size += options->path.len;
@@ -142,8 +144,8 @@ int aws_uri_init_from_builder_options(
     struct aws_byte_cursor port_app = aws_byte_cursor_from_c_str(":");
     if (options->port) {
         aws_byte_buf_append(&uri->uri_str, &port_app);
-        char port_arr[6] = {0};
-        snprintf(port_arr, sizeof(port_arr), "%" PRIu16, options->port);
+        char port_arr[PORT_BUFFER_SIZE] = {0};
+        snprintf(port_arr, sizeof(port_arr), "%" PRIu32, options->port);
         struct aws_byte_cursor port_csr = aws_byte_cursor_from_c_str(port_arr);
         aws_byte_buf_append(&uri->uri_str, &port_csr);
     }
@@ -208,7 +210,7 @@ const struct aws_byte_cursor *aws_uri_host_name(const struct aws_uri *uri) {
     return &uri->host_name;
 }
 
-uint16_t aws_uri_port(const struct aws_uri *uri) {
+uint32_t aws_uri_port(const struct aws_uri *uri) {
     return uri->port;
 }
 
@@ -385,31 +387,23 @@ static void s_parse_authority(struct uri_parser *parser, struct aws_byte_cursor
 
         size_t port_len = authority_parse_csr.len - parser->uri->host_name.len - 1;
         port_delim += 1;
-        for (size_t i = 0; i < port_len; ++i) {
-            if (!aws_isdigit(port_delim[i])) {
+
+        uint64_t port_u64 = 0;
+        if (port_len > 0) {
+            struct aws_byte_cursor port_cursor = aws_byte_cursor_from_array(port_delim, port_len);
+            if (aws_byte_cursor_utf8_parse_u64(port_cursor, &port_u64)) {
+                parser->state = ERROR;
+                aws_raise_error(AWS_ERROR_MALFORMED_INPUT_STRING);
+                return;
+            }
+            if (port_u64 > UINT32_MAX) {
                 parser->state = ERROR;
                 aws_raise_error(AWS_ERROR_MALFORMED_INPUT_STRING);
                 return;
             }
         }
 
-        if (port_len > 5) {
-            parser->state = ERROR;
-            aws_raise_error(AWS_ERROR_MALFORMED_INPUT_STRING);
-            return;
-        }
-
-        /* why 6? because the port is a 16-bit unsigned integer*/
-        char atoi_buf[6] = {0};
-        memcpy(atoi_buf, port_delim, port_len);
-        int port_int = atoi(atoi_buf);
-        if (port_int > UINT16_MAX) {
-            parser->state = ERROR;
-            aws_raise_error(AWS_ERROR_MALFORMED_INPUT_STRING);
-            return;
-        }
-
-        parser->uri->port = (uint16_t)port_int;
+        parser->uri->port = (uint32_t)port_u64;
     }
 }
 
diff --git a/tests/uri_test.c b/tests/uri_test.c
index a9434f27f..293f6a822 100644
--- a/tests/uri_test.c
+++ b/tests/uri_test.c
@@ -582,7 +582,7 @@ AWS_TEST_CASE(uri_invalid_port_parse, s_test_uri_invalid_port_parse);
 
 static int s_test_uri_port_too_large_parse(struct aws_allocator *allocator, void *ctx) {
     (void)ctx;
-    const char *str_uri = "https://www.test.com:844356/path/to/"
+    const char *str_uri = "https://www.test.com:4294967296/path/to/"
                           "resource?test1=value1&test%20space=value%20space&test2=value2&test2=value3";
 
     struct aws_byte_cursor uri_csr = aws_byte_cursor_from_c_str(str_uri);