diff --git a/main.cpp b/main.cpp
index bb5698f..6f04c3b 100644
--- a/main.cpp
+++ b/main.cpp
@@ -16,6 +16,8 @@
 
 #include <libbladeRF.h>
 
+#define POCKETFFT_CACHE_SIZE (16*1024*1024)
+#define POCKETFFT_NO_MULTITHREADING  // MT doesn't seem to help at small sizes
 #include <pocketfft_hdronly.h>