diff --git a/util/StringUtil.cc b/util/StringUtil.cc
index 02c5edfc..bdde20e1 100644
--- a/util/StringUtil.cc
+++ b/util/StringUtil.cc
@@ -20,12 +20,15 @@
 #include <cctype>
 #include <cstdio>
 #include <array>
+#include <algorithm>
 
 #include "Machine.hh"
 #include "Mutex.hh"
 
 namespace sta {
 
+using std::max;
+
 static void
 stringPrintTmp(const char *fmt,
 	       va_list args,
@@ -199,9 +202,10 @@ makeTmpString(size_t length)
   if (tmp_length < length) {
     // String isn't long enough.  Make a new one.
     delete [] tmp_str;
-    tmp_str = new char[length];
+    tmp_length = max(tmp_string_initial_length, length);
+    tmp_str = new char[tmp_length];
     tmp_strings[tmp_string_next] = tmp_str;
-    tmp_string_lengths[tmp_string_next] = length;
+    tmp_string_lengths[tmp_string_next] = tmp_length;
   }
   tmp_string_next++;
   return tmp_str;