diff --git a/src/V3Ast.h b/src/V3Ast.h
index 538998755..c22cb256c 100644
--- a/src/V3Ast.h
+++ b/src/V3Ast.h
@@ -968,6 +968,7 @@ public:
 
     // METHODS - queries
     virtual bool isPure() const { return true; }	// Else a $display, etc, that must be ordered with other displays
+    virtual bool isBrancher() const { return false; }	// Changes control flow, disable some optimizations
     virtual bool isGateOptimizable() const { return true; }	// Else a AstTime etc that can't be pushed out
     virtual bool isSubstOptimizable() const { return true; }	// Else a AstTime etc that can't be substituted out
     virtual bool isPredictOptimizable() const { return true; }	// Else a AstTime etc which output can't be predicted from input
diff --git a/src/V3AstNodes.h b/src/V3AstNodes.h
index 47dadf379..679ceefec 100644
--- a/src/V3AstNodes.h
+++ b/src/V3AstNodes.h
@@ -2040,7 +2040,7 @@ struct AstBreak : public AstNodeStmt {
     ASTNODE_NODE_FUNCS(Break, BREAK)
     virtual string verilogKwd() const { return "break"; };
     virtual V3Hash sameHash() const { return V3Hash(); }
-    virtual bool isPure() const { return false; }	// SPECIAL: We don't process code after breaks
+    virtual bool isBrancher() const { return true; }	// SPECIAL: We don't process code after breaks
 };
 
 struct AstContinue : public AstNodeStmt {
@@ -2049,7 +2049,7 @@ struct AstContinue : public AstNodeStmt {
     ASTNODE_NODE_FUNCS(Continue, CONTINUE)
     virtual string verilogKwd() const { return "continue"; };
     virtual V3Hash sameHash() const { return V3Hash(); }
-    virtual bool isPure() const { return false; }	// SPECIAL: We don't process code after breaks
+    virtual bool isBrancher() const { return true; }	// SPECIAL: We don't process code after breaks
 };
 
 struct AstDisable : public AstNodeStmt {
@@ -2061,7 +2061,7 @@ public:
     ASTNODE_NODE_FUNCS(Disable, DISABLE)
     virtual string name()	const { return m_name; }		// * = Block name
     void name(const string& flag) { m_name=flag; }
-    virtual bool isPure() const { return false; }	// SPECIAL: We don't process code after breaks
+    virtual bool isBrancher() const { return true; }	// SPECIAL: We don't process code after breaks
 };
 
 struct AstReturn : public AstNodeStmt {
@@ -2073,7 +2073,7 @@ struct AstReturn : public AstNodeStmt {
     virtual string verilogKwd() const { return "return"; };
     virtual V3Hash sameHash() const { return V3Hash(); }
     AstNode*	lhsp() const { return op1p(); }
-    virtual bool isPure() const { return false; }	// SPECIAL: We don't process code after breaks
+    virtual bool isBrancher() const { return true; }	// SPECIAL: We don't process code after breaks
 };
 
 struct AstGenIf : public AstNodeIf {
@@ -2145,7 +2145,7 @@ public:
     virtual bool same(AstNode* samep) const {  // Also same if identical tree structure all the way down, but hard to detect
 	return labelp()==samep->castJumpGo()->labelp(); }
     virtual bool isGateOptimizable() const { return false; }
-    virtual bool isPure() const { return false; }	// SPECIAL: We don't process code after breaks
+    virtual bool isBrancher() const { return true; }	// SPECIAL: We don't process code after breaks
     AstJumpLabel* labelp() const { return m_labelp; }
 };
 
diff --git a/src/V3ClkGater.cpp b/src/V3ClkGater.cpp
index b352524fb..192c0f2d0 100644
--- a/src/V3ClkGater.cpp
+++ b/src/V3ClkGater.cpp
@@ -862,7 +862,7 @@ class GaterVisitor : public GaterBaseVisitor {
 	    m_stmtVscp = NULL;
 	    m_stmtInPli = false;
 	}
-	if (!nodep->isPure()) {
+	if (!nodep->isPure() || nodep->isBrancher()) {
 	    // May also be a new statement (above if); if so we mark it immediately
 	    UINFO(9,"         NotPure "<<nodep<<endl);
 	    scoreboardPli(nodep);
diff --git a/src/V3Gate.cpp b/src/V3Gate.cpp
index c659fccd6..19da4978e 100644
--- a/src/V3Gate.cpp
+++ b/src/V3Gate.cpp
@@ -195,7 +195,8 @@ private:
 	// *** Special iterator
 	if (!m_isSimple) return;	// Fastpath
 	if (!nodep->isGateOptimizable()
-	    || !nodep->isPure()) {
+	    || !nodep->isPure()
+	    || nodep->isBrancher()) {
 	    UINFO(5, "Non optimizable type: "<<nodep<<endl);
 	    clearSimple("Non optimizable type");
 	}