diff --git a/include/sta/PatternMatch.hh b/include/sta/PatternMatch.hh
index bfd265c2..708e8686 100644
--- a/include/sta/PatternMatch.hh
+++ b/include/sta/PatternMatch.hh
@@ -16,6 +16,7 @@
 
 #pragma once
 
+#include <string>
 #include "DisallowCopyAssign.hh"
 #include "Error.hh"
 
@@ -67,12 +68,12 @@ private:
 class RegexpCompileError : public Exception
 {
 public:
-  explicit RegexpCompileError(const char *error);
+  explicit RegexpCompileError(const char *pattern);
   virtual ~RegexpCompileError() noexcept {}
   virtual const char *what() const noexcept;
 
 private:
-  const char *error_;
+  std::string error_;
 };
 
 // Simple pattern match
diff --git a/util/PatternMatch.cc b/util/PatternMatch.cc
index d5e9c4c7..c8cb1ce0 100644
--- a/util/PatternMatch.cc
+++ b/util/PatternMatch.cc
@@ -16,13 +16,8 @@
 
 #include "PatternMatch.hh"
 
-#include <string.h>
-#include <string>
-#include <ctype.h>
 #include <tcl.h>
 
-#include "StringUtil.hh"
-
 namespace sta {
 
 using std::string;
@@ -117,13 +112,15 @@ PatternMatch::matchNoCase(const char *str) const
 RegexpCompileError::RegexpCompileError(const char *pattern)  :
   Exception()
 {
-  error_ = stringPrint("TCL failed to compile regular expression '%s'.", pattern);
+  error_ = "TCL failed to compile regular expression '";
+  error_ += pattern;
+  error_ =+ "'.";
 }
 
 const char *
 RegexpCompileError::what() const noexcept
 {
-  return error_;
+  return error_.c_str();
 }
 
 ////////////////////////////////////////////////////////////////