diff --git a/include/sta/PathGroup.hh b/include/sta/PathGroup.hh
index a3bd6ee3..836804f7 100644
--- a/include/sta/PathGroup.hh
+++ b/include/sta/PathGroup.hh
@@ -32,6 +32,7 @@
 #include "SdcClass.hh"
 #include "StaState.hh"
 #include "SearchClass.hh"
+#include "StringUtil.hh"
 
 namespace sta {
 
@@ -42,7 +43,6 @@ using PathGroupIterator = PathEndSeq::iterator;
 using PathGroupClkMap = std::map<const Clock*, PathGroup*>;
 using PathGroupNamedMap = std::map<const char*, PathGroup*, CharPtrLess>;
 using PathGroupSeq = std::vector<PathGroup*>;
-using StdStringSeq = std::vector<std::string>;
 
 // A collection of PathEnds grouped and sorted for reporting.
 class PathGroup
diff --git a/include/sta/Search.hh b/include/sta/Search.hh
index 09bc1687..4c98845c 100644
--- a/include/sta/Search.hh
+++ b/include/sta/Search.hh
@@ -40,6 +40,7 @@
 #include "SearchPred.hh"
 #include "VertexVisitor.hh"
 #include "Path.hh"
+#include "StringUtil.hh"
 
 namespace sta {
 
@@ -70,7 +71,6 @@ using VertexSlackMapSeq = std::vector<VertexSlackMap>;
 using WorstSlacksSeq = std::vector<WorstSlacks>;
 using DelayDblSeq = std::vector<DelayDbl>;
 using ExceptionPathSeq = std::vector<ExceptionPath*>;
-using StdStringSeq = std::vector<std::string>;
 
 class Search : public StaState
 {
diff --git a/include/sta/Sta.hh b/include/sta/Sta.hh
index 15df9a85..ddb2f7d7 100644
--- a/include/sta/Sta.hh
+++ b/include/sta/Sta.hh
@@ -30,6 +30,7 @@
 #include <functional>
 
 #include "StringSeq.hh"
+#include "StringUtil.hh"
 #include "LibertyClass.hh"
 #include "NetworkClass.hh"
 #include "SdcClass.hh"
@@ -80,7 +81,6 @@ using SceneNameMap = std::map<std::string, Scene*>;
 using SlowDrvrIterator = Iterator<Instance*>;
 using CheckError = StringSeq;
 using CheckErrorSeq = std::vector<CheckError*>;
-using StdStringSeq = std::vector<std::string>;
 enum class CmdNamespace { sta, sdc };
 using ParasiticsNameMap = std::map<std::string, Parasitics*>;
 // Path::slack/arrival/required function.
diff --git a/include/sta/StringSeq.hh b/include/sta/StringSeq.hh
index ca7c304f..9821b7b2 100644
--- a/include/sta/StringSeq.hh
+++ b/include/sta/StringSeq.hh
@@ -31,7 +31,6 @@
 namespace sta {
 
 using StringSeq = std::vector<const char*>;
-using StdStringSeq = std::vector<std::string>;
 
 void
 deleteContents(StringSeq *strings);
diff --git a/include/sta/StringSet.hh b/include/sta/StringSet.hh
index 36fa7e67..fc3d0d2b 100644
--- a/include/sta/StringSet.hh
+++ b/include/sta/StringSet.hh
@@ -31,7 +31,6 @@ namespace sta {
 
 using StringSet = std::set<const char*, CharPtrLess>;
 using StdStringSet = std::set<std::string>;
-using StdStringSeq = std::vector<std::string>;
 
 void
 deleteContents(StringSet *strings);
diff --git a/liberty/LibertyReaderPvt.hh b/liberty/LibertyReaderPvt.hh
index 91fdf260..c17cdeb8 100644
--- a/liberty/LibertyReaderPvt.hh
+++ b/liberty/LibertyReaderPvt.hh
@@ -31,6 +31,7 @@
 #include <unordered_map>
 
 #include "StringSeq.hh"
+#include "StringUtil.hh"
 #include "MinMax.hh"
 #include "NetworkClass.hh"
 #include "Transition.hh"
@@ -55,7 +56,6 @@ class OutputWaveform;
 using LibraryGroupVisitor = void (LibertyReader::*)(const LibertyGroup *group,
                                                     LibertyGroup *parent_group);
 using LibraryGroupVisitorMap = std::unordered_map<std::string, LibraryGroupVisitor>;
-using StdStringSeq = std::vector<std::string>;
 using LibertyPortGroupMap = std::map<const LibertyGroup*, LibertyPortSeq,
                                      LibertyGroupLineLess>;
 using OutputWaveformSeq = std::vector<OutputWaveform>;
diff --git a/spice/WriteSpice.hh b/spice/WriteSpice.hh
index aee55dfe..81bd15b7 100644
--- a/spice/WriteSpice.hh
+++ b/spice/WriteSpice.hh
@@ -31,6 +31,7 @@
 
 #include "StaState.hh"
 #include "StringSet.hh"
+#include "StringUtil.hh"
 #include "Liberty.hh"
 #include "GraphClass.hh"
 #include "Parasitics.hh"
@@ -40,7 +41,6 @@
 namespace sta {
 
 using ParasiticNodeMap = std::map<const ParasiticNode*, int>;
-using StdStringSeq = std::vector<std::string>;
 using CellSpicePortNames = std::map<std::string, StdStringSeq>;
 using LibertyPortLogicValues = std::map<const LibertyPort*, LogicValue>;
 
diff --git a/spice/Xyce.hh b/spice/Xyce.hh
index 1c27cb4e..ce8e5e6c 100644
--- a/spice/Xyce.hh
+++ b/spice/Xyce.hh
@@ -27,11 +27,11 @@
 #include <string>
 #include <vector>
 
+#include "StringUtil.hh"
 #include "TableModel.hh"
 
 namespace sta {
 
-using StdStringSeq = std::vector<std::string>;
 using WaveformSeq = std::vector<Table>;
 
 void
diff --git a/verilog/VerilogReaderPvt.hh b/verilog/VerilogReaderPvt.hh
index 60498c7d..6bbe8288 100644
--- a/verilog/VerilogReaderPvt.hh
+++ b/verilog/VerilogReaderPvt.hh
@@ -29,12 +29,12 @@
 #include <map>
 
 #include "StringSeq.hh"
+#include "StringUtil.hh"
 
 namespace sta {
 
 using VerilogDclMap = std::map<std::string, VerilogDcl*>;
 using VerilogConstantValue = std::vector<bool>;
-using StdStringSeq = std::vector<std::string>;
 
 class VerilogStmt
 {