diff --git a/pkgs/by-name/re/rep-gtk/package.nix b/pkgs/by-name/re/rep-gtk/package.nix
index 4d8cfc0a7699..872eacb5011e 100644
--- a/pkgs/by-name/re/rep-gtk/package.nix
+++ b/pkgs/by-name/re/rep-gtk/package.nix
@@ -29,6 +29,13 @@ stdenv.mkDerivation (finalAttrs: {
 
   strictDeps = true;
 
+  env.NIX_CFLAGS_COMPILE = toString (
+    lib.optionals stdenv.cc.isClang [
+      "-Wno-error=implicit-function-declaration"
+      "-Wno-error=int-conversion"
+    ]
+  );
+
   patchPhase = ''
     sed -e 's|installdir=$(repexecdir)|installdir=$(libdir)/rep|g' -i Makefile.in
   '';