diff --git a/Changes b/Changes
index 76ffd1dd8..10968aabc 100644
--- a/Changes
+++ b/Changes
@@ -15,6 +15,8 @@ indicates the contributor was also the author of the fix; Thanks!
 
 ****  Fix missing VL_SHIFTRS_IQI with WIDTH warning, bug714. [Fabrizio Ferrandi]
 
+****  Fix signed shift right optimization, bug715. [Fabrizio Ferrandi]
+
 ****  Fix internal error on "input x =" syntax error, bug716. [Lane Brooks]
 
 ****  Fix slice extraction from packed array, bug717. [Jan Egil Ruud]
diff --git a/include/verilated.h b/include/verilated.h
index 892d0d397..364a8994f 100644
--- a/include/verilated.h
+++ b/include/verilated.h
@@ -1455,32 +1455,37 @@ static inline WDataOutP VL_SHIFTR_WWI(int obits,int,int,WDataOutP owp,WDataInP l
 }
 
 // EMIT_RULE: VL_SHIFTRS:  oclean=false; lclean=clean, rclean==clean;
-static inline IData VL_SHIFTRS_III(int obits, int, int, IData lhs, IData rhs) {
+static inline IData VL_SHIFTRS_III(int obits, int lbits, int, IData lhs, IData rhs) {
     // Note the C standard does not specify the >> operator as a arithmetic shift!
-    IData sign    = -(lhs >> (obits-1)); // ffff_ffff if negative
-    IData signext = ~(VL_MASK_I(obits) >> rhs);   // One with bits where we've shifted "past"
+    // IEEE says signed if output signed, but bit position from lbits;
+    // must use lbits for sign; lbits might != obits,
+    // an EXTEND(SHIFTRS(...)) can became a SHIFTRS(...) within same 32/64 bit word length
+    IData sign    = -(lhs >> (lbits-1)); // ffff_ffff if negative
+    IData signext = ~(VL_MASK_I(lbits) >> rhs);   // One with bits where we've shifted "past"
     return (lhs >> rhs) | (sign & VL_CLEAN_II(obits,obits,signext));
 }
-static inline QData VL_SHIFTRS_QQI(int obits, int, int, QData lhs, IData rhs) {
-    QData sign    = -(lhs >> (obits-1));
-    QData signext = ~(VL_MASK_Q(obits) >> rhs);
+static inline QData VL_SHIFTRS_QQI(int obits, int lbits, int, QData lhs, IData rhs) {
+    QData sign    = -(lhs >> (lbits-1));
+    QData signext = ~(VL_MASK_Q(lbits) >> rhs);
     return (lhs >> rhs) | (sign & VL_CLEAN_QQ(obits,obits,signext));
 }
 static inline IData VL_SHIFTRS_IQI(int obits, int lbits, int rbits, QData lhs, IData rhs) {
     return (IData)(VL_SHIFTRS_QQI(obits, lbits, rbits, lhs, rhs));
 }
-static inline WDataOutP VL_SHIFTRS_WWI(int obits,int,int,WDataOutP owp,WDataInP lwp, IData rd) {
+static inline WDataOutP VL_SHIFTRS_WWI(int obits,int lbits,int,WDataOutP owp,WDataInP lwp, IData rd) {
     int word_shift = VL_BITWORD_I(rd);
     int bit_shift = VL_BITBIT_I(rd);
     int lmsw = VL_WORDS_I(obits)-1;
-    IData sign = VL_SIGNONES_I(obits,lwp[lmsw]);
-    if ((int)rd >= obits) {
+    IData sign = VL_SIGNONES_I(lbits,lwp[lmsw]);
+    if ((int)rd >= obits) {  // Shifting past end, sign in all of lbits
 	for (int i=0; i <= lmsw; i++) owp[i] = sign;
+	owp[lmsw] &= VL_MASK_I(lbits);
     } else if (bit_shift==0) {  // Aligned word shift (>>0,>>32,>>64 etc)
 	int copy_words = (VL_WORDS_I(obits)-word_shift);
 	for (int i=0; i < copy_words; i++) owp[i] = lwp[i+word_shift];
 	if (copy_words>=0) owp[copy_words-1] |= ~VL_MASK_I(obits) & sign;
 	for (int i=copy_words; i < VL_WORDS_I(obits); i++) owp[i] = sign;
+	owp[lmsw] &= VL_MASK_I(lbits);
     } else {
 	int loffset = rd & VL_SIZEBITS_I;
 	int nbitsonright = 32-loffset;  // bits that end up in lword (know loffset!=0)
@@ -1495,6 +1500,7 @@ static inline WDataOutP VL_SHIFTRS_WWI(int obits,int,int,WDataOutP owp,WDataInP
 	}
 	if (words) owp[words-1] |= sign & ~VL_MASK_I(obits-loffset);
 	for (int i=words; i<VL_WORDS_I(obits); i++) owp[i] = sign;
+	owp[lmsw] &= VL_MASK_I(lbits);
     }
     return(owp);
 }
diff --git a/src/V3AstNodes.h b/src/V3AstNodes.h
index ccf906dfa..7402fa0f3 100644
--- a/src/V3AstNodes.h
+++ b/src/V3AstNodes.h
@@ -3849,6 +3849,8 @@ struct AstShiftR : public AstNodeBiop {
     virtual bool sizeMattersLhs() {return false;} virtual bool sizeMattersRhs() {return false;}  // LHS size might be > output size, so don't want to force size
 };
 struct AstShiftRS : public AstNodeBiop {
+    // Shift right with sign extension, >>> operator
+    // Output data type's width determines which bit is used for sign extension
     AstShiftRS(FileLine* fl, AstNode* lhsp, AstNode* rhsp, int setwidth=0)
 	: AstNodeBiop(fl, lhsp, rhsp) {
 	if (setwidth) { dtypeSetLogicSized(setwidth,setwidth,AstNumeric::SIGNED); }
diff --git a/src/V3Const.cpp b/src/V3Const.cpp
index 1f4e517e6..e68c0dada 100644
--- a/src/V3Const.cpp
+++ b/src/V3Const.cpp
@@ -538,6 +538,8 @@ private:
     void replaceWChild(AstNode* nodep, AstNode* childp) {
 	// NODE(..., CHILD(...)) -> CHILD(...)
 	childp->unlinkFrBackWithNext();
+	// If replacing a SEL for example, the data type comes from the parent (is less wide).
+	// This may adversly affect the operation of the node being replaced.
 	childp->dtypeFrom(nodep);
 	nodep->replaceWith(childp);
 	nodep->deleteTree(); nodep=NULL;
@@ -1831,7 +1833,7 @@ private:
     TREEOP1("AstGte  {$lhsp.isAllOnes, $rhsp, $lhsp->width()==$rhsp->width()}",  "replaceNumLimited(nodep,1)");
     // Two level bubble pushing
     TREEOP ("AstNot   {$lhsp.castNot,  $lhsp->width()==$lhsp->castNot()->lhsp()->width()}",	"replaceWChild(nodep, $lhsp->op1p())");  // NOT(NOT(x))->x
-    TREEOP ("AstLogNot{$lhsp.castLogNot}",		"replaceWChild(nodep, $lhsp->op1p())");  // NOT(NOT(x))->x
+    TREEOP ("AstLogNot{$lhsp.castLogNot}",		"replaceWChild(nodep, $lhsp->op1p())");  // LOGNOT(LOGNOT(x))->x
     TREEOPV("AstNot   {$lhsp.castEqCase, $lhsp.width1}","AstNeqCase{$lhsp->op1p(),$lhsp->op2p()}");
     TREEOP ("AstLogNot{$lhsp.castEqCase}",		"AstNeqCase{$lhsp->op1p(),$lhsp->op2p()}");
     TREEOPV("AstNot   {$lhsp.castNeqCase, $lhsp.width1}","AstEqCase {$lhsp->op1p(),$lhsp->op2p()}");