diff --git a/sim/rfnoc/PkgAxiStreamBfm.sv b/sim/rfnoc/PkgAxiStreamBfm.sv
index d1ca071..0470a3d 100644
--- a/sim/rfnoc/PkgAxiStreamBfm.sv
+++ b/sim/rfnoc/PkgAxiStreamBfm.sv
@@ -85,8 +85,11 @@ package PkgAxiStreamBfm;
     // Type Definitions
     //------------------
 
+    // Round up width of TKEEP when TDATA is not a multiple of 8
+    localparam int KEEP_WIDTH = (DATA_WIDTH+7)/8;
+
     typedef logic [DATA_WIDTH-1:0]   data_t;  // Single bus TDATA word
-    typedef logic [DATA_WIDTH/8-1:0] keep_t;  // Single TKEEP word
+    typedef logic [KEEP_WIDTH-1:0]   keep_t;  // Single TKEEP word
     typedef logic [USER_WIDTH-1:0]   user_t;  // Single TUSER word
 
     typedef AxiStreamPacket #(DATA_WIDTH, USER_WIDTH) AxisPacket_t;
@@ -285,13 +288,15 @@ package PkgAxiStreamBfm;
     // Properties
     //------------
 
+    localparam int KEEP_WIDTH = AxisPacket_t::KEEP_WIDTH;
+
     // Default stall probability, as a percentage (0-100).
     local const int DEF_STALL_PROB = 38;
 
     // Default values to use for idle bus cycles
     local const AxisPacket_t::data_t IDLE_DATA = {DATA_WIDTH{1'bX}};
     local const AxisPacket_t::user_t IDLE_USER = {(USER_WIDTH > 1 ? USER_WIDTH : 1){1'bX}};
-    local const AxisPacket_t::keep_t IDLE_KEEP = {(DATA_WIDTH/8){1'bX}};
+    local const AxisPacket_t::keep_t IDLE_KEEP = {KEEP_WIDTH{1'bX}};
 
     // Virtual interfaces for master and slave connections to DUT
     local virtual AxiStreamIf #(DATA_WIDTH,USER_WIDTH,MAX_PACKET_BYTES,