diff --git a/vvp/opcodes.txt b/vvp/opcodes.txt
index c7b2baf50..b0ed5702f 100644
--- a/vvp/opcodes.txt
+++ b/vvp/opcodes.txt
@@ -1106,8 +1106,6 @@ The instruction also checks flag bit 4. If it is true, the result is
 replaced with X instead of a shifted result. This is intended to
 detect that the index contents were not valid.
 
-For a negative shift, %shiftr will pad the value with 'bx.
-
 * %split/vec4 <wid>
 
 Pull the top vec4 vector from the stack and split it into two
diff --git a/vvp/vthread.cc b/vvp/vthread.cc
index 2051b1176..5e7507752 100644
--- a/vvp/vthread.cc
+++ b/vvp/vthread.cc
@@ -5402,10 +5402,10 @@ bool of_SET_DAR_OBJ_STR(vthread_t thr, vvp_code_t cp)
 bool of_SHIFTL(vthread_t thr, vvp_code_t cp)
 {
       int use_index = cp->number;
-      int shift = thr->words[use_index].w_int;
+      uint64_t shift = thr->words[use_index].w_uint;
 
       vvp_vector4_t&val = thr->peek_vec4();
-      int wid  = val.size();
+      unsigned wid  = val.size();
 
       if (thr->flags[4] == BIT4_1) {
 	      // The result is 'bx if the shift amount is undefined
@@ -5421,18 +5421,6 @@ bool of_SHIFTL(vthread_t thr, vvp_code_t cp)
 	    vvp_vector4_t tmp (shift, BIT4_0);
 	    val.set_vec(0, tmp);
 	    val.set_vec(shift, blk);
-
-      } else if (shift < -wid) {
-	    val = vvp_vector4_t(wid, BIT4_X);
-
-      } else if (shift < 0) {
-	      // Negative left shift is a right shift.
-	      // For a negative shift, we pad with 'bx.
-	    int use_shift = -shift;
-	    vvp_vector4_t blk = val.subvalue(use_shift, wid-use_shift);
-	    vvp_vector4_t tmp (use_shift, BIT4_X);
-	    val.set_vec(0, blk);
-	    val.set_vec(wid-use_shift, tmp);
       }
 
       return true;
@@ -5447,10 +5435,10 @@ bool of_SHIFTL(vthread_t thr, vvp_code_t cp)
 bool of_SHIFTR(vthread_t thr, vvp_code_t cp)
 {
       int use_index = cp->number;
-      int shift = thr->words[use_index].w_int;
+      uint64_t shift = thr->words[use_index].w_uint;
 
       vvp_vector4_t val = thr->pop_vec4();
-      int wid  = val.size();
+      unsigned wid  = val.size();
 
       if (thr->flags[4] == BIT4_1) {
 	    val = vvp_vector4_t(wid, BIT4_X);
@@ -5463,18 +5451,6 @@ bool of_SHIFTR(vthread_t thr, vvp_code_t cp)
 	    vvp_vector4_t tmp (shift, BIT4_0);
 	    val.set_vec(0, blk);
 	    val.set_vec(wid-shift, tmp);
-
-      } else if (shift < -wid) {
-	    val = vvp_vector4_t(wid, BIT4_X);
-
-      } else if (shift < 0) {
-	      // Negative right shift is a left shift.
-	      // For a negative shift, we pad with 'bx.
-	    int use_shift = -shift;
-	    vvp_vector4_t blk = val.subvalue(0, wid-use_shift);
-	    vvp_vector4_t tmp (use_shift, BIT4_X);
-	    val.set_vec(0, tmp);
-	    val.set_vec(use_shift, blk);
       }
 
       thr->push_vec4(val);
@@ -5487,10 +5463,10 @@ bool of_SHIFTR(vthread_t thr, vvp_code_t cp)
 bool of_SHIFTR_S(vthread_t thr, vvp_code_t cp)
 {
       int use_index = cp->number;
-      int shift = thr->words[use_index].w_int;
+      uint64_t shift = thr->words[use_index].w_uint;
 
       vvp_vector4_t val = thr->pop_vec4();
-      int wid  = val.size();
+      unsigned wid  = val.size();
 
       vvp_bit4_t sign_bit = val.value(val.size()-1);
 
@@ -5505,16 +5481,6 @@ bool of_SHIFTR_S(vthread_t thr, vvp_code_t cp)
 	    vvp_vector4_t tmp (shift, sign_bit);
 	    val.set_vec(0, blk);
 	    val.set_vec(wid-shift, tmp);
-
-      } else if (shift < -wid) {
-	    val = vvp_vector4_t(wid, BIT4_X);
-
-      } else if (shift < 0) {
-	    int use_shift = -shift;
-	    vvp_vector4_t blk = val.subvalue(0, wid-use_shift);
-	    vvp_vector4_t tmp(use_shift, BIT4_X);
-	    val.set_vec(0, tmp);
-	    val.set_vec(use_shift, blk);
       }
 
       thr->push_vec4(val);