diff --git a/src/KSPACE/fft3d_wrap.h b/src/KSPACE/fft3d_wrap.h
index bf1cdca8e9..d324eb31c3 100644
--- a/src/KSPACE/fft3d_wrap.h
+++ b/src/KSPACE/fft3d_wrap.h
@@ -39,6 +39,8 @@ class FFT3d : protected Pointers {
 
 E: Could not create 3d FFT plan
 
-The FFT setup in pppm failed.
+The FFT setup for the PPPM solver failed, typically due
+to lack of memory.  This is an unusual error.  Check the
+size of the FFT grid you are requesting.
 
 */