diff --git a/parasitics/SpefParse.yy b/parasitics/SpefParse.yy
index 39ad246f..260a212c 100755
--- a/parasitics/SpefParse.yy
+++ b/parasitics/SpefParse.yy
@@ -27,7 +27,7 @@
 
 #include "Report.hh"
 #include "StringUtil.hh"
-#include "StringSeq.hh"
+#include "StringUtil.hh"
 #include "parasitics/SpefReaderPvt.hh"
 #include "parasitics/SpefScanner.hh"
 
@@ -62,7 +62,7 @@ sta::SpefParse::error(const location_type &loc,
   char *string;
   int integer;
   float number;
-  sta::StringSeq *string_seq;
+  sta::StdStringSeq *std_string_seq;
   sta::PortDirection *port_dir;
   sta::SpefRspfPi *pi;
   sta::SpefTriple *triple;
@@ -105,7 +105,7 @@ sta::SpefParse::error(const location_type &loc,
 
 %type <ch> hchar suffix_bus_delim prefix_bus_delim
 
-%type <string_seq> qstrings
+%type <std_string_seq> qstrings
 %type<port_dir> direction
 
 %type<triple> par_value total_cap
@@ -220,11 +220,14 @@ design_flow:
 
 qstrings:
 	QSTRING
-	{ $$ = new sta::StringSeq;
+	{ $$ = new sta::StdStringSeq;
 	  $$->push_back($1);
+	  sta::stringDelete($1);
 	}
 |	qstrings QSTRING
-	{ $$->push_back($2); }
+	{ $$->push_back($2);
+	  sta::stringDelete($2);
+	}
 ;
 
 hierarchy_div_def:
diff --git a/parasitics/SpefReader.cc b/parasitics/SpefReader.cc
index 7d0751f8..16f7a6dc 100644
--- a/parasitics/SpefReader.cc
+++ b/parasitics/SpefReader.cc
@@ -92,7 +92,6 @@ SpefReader::SpefReader(const std::string &filename,
   cap_scale_(1.0),
   res_scale_(1.0),
   induct_scale_(1.0),
-  design_flow_(nullptr),
   parasitics_(parasitics),
   parasitic_(nullptr)
 {
@@ -101,11 +100,6 @@ SpefReader::SpefReader(const std::string &filename,
 
 SpefReader::~SpefReader()
 {
-  if (design_flow_) {
-    deleteContents(design_flow_);
-    delete design_flow_;
-    design_flow_ = nullptr;
-  }
 }
 
 bool
@@ -297,9 +291,10 @@ SpefReader::portDirection(char *spef_dir)
 }
 
 void
-SpefReader::setDesignFlow(StringSeq *flow)
+SpefReader::setDesignFlow(StdStringSeq *flow)
 {
-  design_flow_ = flow;
+  design_flow_ = std::move(*flow);
+  delete flow;
 }
 
 Pin *
diff --git a/parasitics/SpefReaderPvt.hh b/parasitics/SpefReaderPvt.hh
index f96480c4..de0b8043 100644
--- a/parasitics/SpefReaderPvt.hh
+++ b/parasitics/SpefReaderPvt.hh
@@ -27,7 +27,7 @@
 #include <map>
 
 #include "Zlib.hh"
-#include "StringSeq.hh"
+#include "StringUtil.hh"
 #include "NetworkClass.hh"
 #include "ParasiticsClass.hh"
 #include "StaState.hh"
@@ -82,7 +82,7 @@ public:
   void makeNameMapEntry(const char *index,
                         const char *name);
   const char *nameMapLookup(const char *index);
-  void setDesignFlow(StringSeq *flow_keys);
+  void setDesignFlow(StdStringSeq *flow_keys);
   Pin *findPin(char *name);
   Net *findNet(const char *name);
   void rspfBegin(Net *net,
@@ -139,7 +139,7 @@ private:
   float res_scale_;
   float induct_scale_;
   SpefNameMap name_map_;
-  StringSeq *design_flow_;
+  StdStringSeq design_flow_;
   Parasitics *parasitics_;
   Parasitic *parasitic_;
 };