diff --git a/src/core/uri.c b/src/core/uri.c
index aa6eedb91..0abd8bdcd 100644
--- a/src/core/uri.c
+++ b/src/core/uri.c
@@ -456,7 +456,6 @@ unsigned int uri_port ( const struct uri *uri, unsigned int default_port ) {
  */
 size_t format_uri ( const struct uri *uri, char *buf, size_t len ) {
 	static const char prefixes[URI_FIELDS] = {
-		[URI_OPAQUE] = ':',
 		[URI_PASSWORD] = ':',
 		[URI_PORT] = ':',
 		[URI_QUERY] = '?',
@@ -495,9 +494,9 @@ size_t format_uri ( const struct uri *uri, char *buf, size_t len ) {
 					    ( buf + used ), ( len - used ) );
 
 		/* Suffix this field, if applicable */
-		if ( ( field == URI_SCHEME ) && ( ! uri->opaque ) ) {
+		if ( field == URI_SCHEME ) {
 			used += ssnprintf ( ( buf + used ), ( len - used ),
-					    "://" );
+					    ":%s", ( uri->host ? "//" : "" ) );
 		}
 	}
 
diff --git a/src/tests/uri_test.c b/src/tests/uri_test.c
index 57f211aaf..add6e468c 100644
--- a/src/tests/uri_test.c
+++ b/src/tests/uri_test.c
@@ -610,6 +610,34 @@ static struct uri_test uri_iscsi = {
 	},
 };
 
+/** File URI with relative (opaque) path */
+static struct uri_test uri_file_relative = {
+	"file:script.ipxe",
+	{
+		.scheme = "file",
+		.opaque = "script.ipxe",
+	},
+};
+
+/** File URI with absolute path */
+static struct uri_test uri_file_absolute = {
+	"file:/boot/script.ipxe",
+	{
+		.scheme = "file",
+		.path = "/boot/script.ipxe",
+	},
+};
+
+/** File URI with volume name */
+static struct uri_test uri_file_volume = {
+	"file://hpilo/boot/script.ipxe",
+	{
+		.scheme = "file",
+		.host = "hpilo",
+		.path = "/boot/script.ipxe",
+	},
+};
+
 /** URI with port number */
 static struct uri_port_test uri_explicit_port = {
 	"http://192.168.0.1:8080/boot.php",
@@ -899,6 +927,9 @@ static void uri_test_exec ( void ) {
 	uri_parse_format_dup_ok ( &uri_ipv6_local );
 	uri_parse_ok ( &uri_ipv6_local_non_conforming ); /* Parse only */
 	uri_parse_format_dup_ok ( &uri_iscsi );
+	uri_parse_format_dup_ok ( &uri_file_relative );
+	uri_parse_format_dup_ok ( &uri_file_absolute );
+	uri_parse_format_dup_ok ( &uri_file_volume );
 
 	/** URI port number tests */
 	uri_port_ok ( &uri_explicit_port );