diff --git a/project-flakes/synapse/default.nix b/project-flakes/synapse/default.nix
index 2191ec7..e73441c 100644
--- a/project-flakes/synapse/default.nix
+++ b/project-flakes/synapse/default.nix
@@ -23,6 +23,7 @@
     gcc
     # Needed for building `ruff`
     gnumake
+    libiconvReal
 
     # Native dependencies for running Synapse.
     icu