diff --git a/src/util/infix.h b/src/util/infix.h
index 0ff47c646c1..6122c0e35bb 100644
--- a/src/util/infix.h
+++ b/src/util/infix.h
@@ -12,12 +12,9 @@ Author: Chris Smowton, chris.smowton@diffblue.com
 #ifndef CPROVER_UTIL_INFIX_H
 #define CPROVER_UTIL_INFIX_H
 
-#include <string>
+#include <string_view>
 
-inline bool has_infix(
-  const std::string &s,
-  const std::string &infix,
-  size_t offset)
+inline bool has_infix(std::string_view s, std::string_view infix, size_t offset)
 {
   return s.compare(offset, infix.size(), infix)==0;
 }
diff --git a/src/util/prefix.h b/src/util/prefix.h
index b94c1cd93d2..3d49f1949c1 100644
--- a/src/util/prefix.h
+++ b/src/util/prefix.h
@@ -10,11 +10,11 @@ Author: Daniel Kroening, kroening@kroening.com
 #ifndef CPROVER_UTIL_PREFIX_H
 #define CPROVER_UTIL_PREFIX_H
 
-#include <string>
+#include <string_view>
 
-// C++20 will have std::string::starts_with
+// C++20 will have std::string_view::starts_with
 
-inline bool has_prefix(const std::string &s, const std::string &prefix)
+inline bool has_prefix(std::string_view s, std::string_view prefix)
 {
   return s.compare(0, prefix.size(), prefix)==0;
 }
diff --git a/src/util/suffix.h b/src/util/suffix.h
index 4ec273d89f9..10fa8f30cdf 100644
--- a/src/util/suffix.h
+++ b/src/util/suffix.h
@@ -12,9 +12,9 @@ Author: Daniel Kroening, kroening@kroening.com
 
 #include <string>
 
-// C++20 will have std::string::ends_with
+// C++20 will have std::string_view::ends_with
 
-inline bool has_suffix(const std::string &s, const std::string &suffix)
+inline bool has_suffix(std::string_view s, std::string_view suffix)
 {
   if(suffix.size()>s.size())
     return false;