diff --git a/src/V3Ast.cpp b/src/V3Ast.cpp
index 4bac79500..83fa35783 100644
--- a/src/V3Ast.cpp
+++ b/src/V3Ast.cpp
@@ -720,7 +720,11 @@ void AstNode::iterateAndNext(AstNVisitor& v, AstNUser* vup) {
     // IMPORTANT: If you replace a node that's the target of this iterator,
     // then the NEW node will be iterated on next, it isn't skipped!
     // if (!this) return;  // Part of for()
-    for (AstNode* nodep=this; nodep;) {
+    // Future versions of this function may require the node to have a back to be iterated;
+    // there's no lower level reason yet though the back must exist.
+    AstNode* nodep=this;
+    if (VL_UNLIKELY(nodep && !nodep->m_backp)) nodep->v3fatalSrc("iterateAndNext node has no back");
+    while (nodep) {
 	AstNode* niterp = nodep;
 	ASTNODE_PREFETCH(nodep->m_nextp);
 	niterp->m_iterpp = &niterp;
@@ -728,7 +732,7 @@ void AstNode::iterateAndNext(AstNVisitor& v, AstNUser* vup) {
 	// accept may do a replaceNode and change niterp on us...
 	if (!niterp) return;
 	niterp->m_iterpp = NULL;
-	if (niterp!=nodep) { // Edited it
+	if (VL_UNLIKELY(niterp!=nodep)) { // Edited it
 	    nodep = niterp;
 	} else {  // Same node, just loop
 	    nodep = niterp->m_nextp;
diff --git a/src/V3Inline.cpp b/src/V3Inline.cpp
index 5d9d1cd39..2ace0c05e 100644
--- a/src/V3Inline.cpp
+++ b/src/V3Inline.cpp
@@ -146,7 +146,7 @@ private:
 	    }
 	    // Cleanup var names, etc, to not conflict
 	    m_cellp = nodep;
-	    newmodp->iterateAndNext(*this);
+	    newmodp->iterate(*this);   // Not iterateAndNext because newmodp isn't linked; no back
 	    m_cellp = NULL;
 	    // Move statements to top module
 	    if (debug()>=9) { newmodp->dumpTree(cout,"fixmod:"); }
diff --git a/src/V3Task.cpp b/src/V3Task.cpp
index e4a8d3e24..7cb90bfeb 100644
--- a/src/V3Task.cpp
+++ b/src/V3Task.cpp
@@ -243,7 +243,7 @@ public:
 	AstNode::user3ClearTree();
 	AstNode::user4ClearTree();
 	//
-	nodep->iterateAndNext(*this, NULL);
+	nodep->accept(*this);
 	//
 	m_callGraph.removeRedundantEdgesSum(&TaskEdge::followAlwaysTrue);
 	m_callGraph.dumpDotFilePrefixed("task_call");
@@ -280,8 +280,8 @@ private:
     }
 public:
     // CONSTUCTORS
-    TaskRelinkVisitor(AstNode* nodep) {
-	nodep->iterateAndNext(*this, NULL);
+    TaskRelinkVisitor(AstBegin* nodep) {  // Passed temporary tree
+	nodep->accept(*this);
     }
     virtual ~TaskRelinkVisitor() {}
 };
@@ -430,7 +430,12 @@ private:
 	    refp->taskp()->castFunc()->fvarp()->user2p(outvscp);
 	}
 	// Replace variable refs
-	TaskRelinkVisitor visit (beginp);
+	// Iteration requires a back, so put under temporary node
+	{	
+	    AstBegin* tempp = new AstBegin(beginp->fileline(),"[EditWrapper]",beginp);
+	    TaskRelinkVisitor visit (tempp);
+	    tempp->stmtsp()->unlinkFrBackWithNext(); tempp->deleteTree(); tempp=NULL;
+	}
 	//
 	if (debug()>=9) { beginp->dumpTree(cout,"-iotask: "); }
 	return beginp;
@@ -582,7 +587,12 @@ private:
 					      new AstVarRef(rtnvscp->fileline(), rtnvscp, false)));
 	}
 	// Replace variable refs
-	TaskRelinkVisitor visit (cfuncp);
+	// Iteration requires a back, so put under temporary node
+	{	
+	    AstBegin* tempp = new AstBegin(cfuncp->fileline(),"[EditWrapper]",cfuncp);
+	    TaskRelinkVisitor visit (tempp);
+	    tempp->stmtsp()->unlinkFrBackWithNext(); tempp->deleteTree(); tempp=NULL;
+	}
 	// Delete rest of cloned task and return new func
 	pushDeletep(nodep); nodep=NULL;
 	if (debug()>=9 &&  forUser) { cfuncp->dumpTree(cout,"-userFunc: "); }
diff --git a/src/V3Unroll.cpp b/src/V3Unroll.cpp
index 59f5795ce..345dabda3 100644
--- a/src/V3Unroll.cpp
+++ b/src/V3Unroll.cpp
@@ -257,9 +257,14 @@ private:
 
 		    m_varValuep = new AstConst(nodep->fileline(), loopValue);
 
-		    m_varModeReplace = true;
-		    oneloopp->iterateAndNext(*this);
-		    m_varModeReplace = false;
+		    // Iteration requires a back, so put under temporary node
+		    if (oneloopp) {	
+			AstBegin* tempp = new AstBegin(oneloopp->fileline(),"[EditWrapper]",oneloopp);
+			m_varModeReplace = true;
+			tempp->stmtsp()->iterateAndNext(*this);
+			m_varModeReplace = false;
+			tempp->stmtsp()->unlinkFrBackWithNext(); tempp->deleteTree(); tempp=NULL;
+		    }
 
 		    if (newbodysp) newbodysp->addNext(oneloopp);
 		    else newbodysp = oneloopp;
diff --git a/src/V3Width.cpp b/src/V3Width.cpp
index ea838b614..374a83f39 100644
--- a/src/V3Width.cpp
+++ b/src/V3Width.cpp
@@ -1169,8 +1169,8 @@ private:
     }
 public:
     // CONSTUCTORS
-    WidthCommitVisitor(AstNode* nodep) {
-	nodep->iterateAndNext(*this, NULL);
+    WidthCommitVisitor(AstNetlist* nodep) {
+	nodep->accept(*this);
     }
     virtual ~WidthCommitVisitor() {}
 };