diff --git a/applications/apertif/designs/apertif_unb1_correlator/src/vhdl/apertif_unb1_correlator.vhd b/applications/apertif/designs/apertif_unb1_correlator/src/vhdl/apertif_unb1_correlator.vhd
index d7b1db48696f15a8cfc43ebcd7beb2381b95074b..054683f366273f71355e12717f0044ffb3a627b7 100644
--- a/applications/apertif/designs/apertif_unb1_correlator/src/vhdl/apertif_unb1_correlator.vhd
+++ b/applications/apertif/designs/apertif_unb1_correlator/src/vhdl/apertif_unb1_correlator.vhd
@@ -175,7 +175,7 @@ ARCHITECTURE str OF apertif_unb1_correlator IS
   CONSTANT c_wpfb_nof_chan          : NATURAL := 1;                    -- = default 0, defines the number of channels (=time-m
   CONSTANT c_wpfb_nof_points        : NATURAL := 64;                   -- = 1024, N point FFT
   CONSTANT c_wpfb_nof_taps          : NATURAL := 8;                    -- = 8 nof taps n the filter
-  CONSTANT c_wpfb_coef_w            : NATURAL := 9;                    --FIXME: 9b does not work; needs updated coefficient files.
+  CONSTANT c_wpfb_coef_w            : NATURAL := 18;                   --FIXME: 9b does not work; needs updated coefficient files.
   CONSTANT c_wpfb_in_dat_w          : NATURAL := 8;                    --FIXME: should be 6b at some point
   CONSTANT c_wpfb_out_dat_w         : NATURAL := 9;                    --FIXME: Could be wider but is currently 9b to avoid the need for quantization: 9b -> mult -> 18b -> accu -> 32b at the corr output.
   CONSTANT c_wpfb_use_separate      : BOOLEAN := FALSE;                -- = false for complex input, true for two real inputs