diff --git a/pkgs/applications/networking/mumble/default.nix b/pkgs/applications/networking/mumble/default.nix
index 20a32159520..37c4c4005ba 100644
--- a/pkgs/applications/networking/mumble/default.nix
+++ b/pkgs/applications/networking/mumble/default.nix
@@ -80,6 +80,8 @@ let
       "CONFIG+=no-server"
     ];
 
+    NIX_CFLAGS_COMPILE = optional speechdSupport "-I${speechd}/include/speech-dispatcher";
+
     installPhase = ''
       cp scripts/mumble-overlay $out/bin
       sed -i "s,/usr/lib,$out/lib,g" $out/bin/mumble-overlay