diff --git a/pkgs/servers/sql/postgresql/ext/pointcloud/package.nix b/pkgs/servers/sql/postgresql/ext/pointcloud/package.nix
index 7e2f75da868d..021f4041b4dd 100644
--- a/pkgs/servers/sql/postgresql/ext/pointcloud/package.nix
+++ b/pkgs/servers/sql/postgresql/ext/pointcloud/package.nix
@@ -67,6 +67,7 @@ postgresqlBuildExtension (finalAttrs: {
 
   configureFlags = [
     (lib.withFeatureAs true "xml2config" (lib.getExe' (lib.getDev libxml2) "xml2-config"))
+    "CFLAGS=-std=gnu17"
   ];
 
   postInstall = ''