diff --git a/c++/src/H5DcreatProp.cpp b/c++/src/H5DcreatProp.cpp
index d670b74263d..71195958eb3 100644
--- a/c++/src/H5DcreatProp.cpp
+++ b/c++/src/H5DcreatProp.cpp
@@ -769,8 +769,8 @@ DSetCreatPropList::setVirtual(const DataSpace &vspace, const char *src_fname, co
 // Programmer   Binh-Minh Ribler - Mar, 2017
 //--------------------------------------------------------------------------
 void
-DSetCreatPropList::setVirtual(const DataSpace &vspace, const H5std_string src_fname,
-                              const H5std_string src_dsname, const DataSpace &sspace) const
+DSetCreatPropList::setVirtual(const DataSpace &vspace, const H5std_string& src_fname,
+                              const H5std_string& src_dsname, const DataSpace &sspace) const
 {
     setVirtual(vspace, src_fname.c_str(), src_dsname.c_str(), sspace);
 }
diff --git a/c++/src/H5DcreatProp.h b/c++/src/H5DcreatProp.h
index 3c032ee5c6d..a0a734dab0b 100644
--- a/c++/src/H5DcreatProp.h
+++ b/c++/src/H5DcreatProp.h
@@ -123,7 +123,7 @@ class H5_DLLCPP DSetCreatPropList : public ObjCreatPropList {
     // Maps elements of a virtual dataset to elements of the source dataset.
     void setVirtual(const DataSpace &vspace, const char *src_fname, const char *src_dsname,
                     const DataSpace &sspace) const;
-    void setVirtual(const DataSpace &vspace, const H5std_string src_fname, const H5std_string src_dsname,
+    void setVirtual(const DataSpace &vspace, const H5std_string& src_fname, const H5std_string& src_dsname,
                     const DataSpace &sspace) const;
 
     ///\brief Returns this class name.
diff --git a/c++/test/dsets.cpp b/c++/test/dsets.cpp
index 03e49277613..2835a1bc7b2 100644
--- a/c++/test/dsets.cpp
+++ b/c++/test/dsets.cpp
@@ -1161,7 +1161,7 @@ const int          RANK1 = 1;
 const H5std_string FILE_ACCPLIST("test_accplist.h5");
 
 static herr_t
-test_chunk_cache(FileAccPropList fapl)
+test_chunk_cache(const FileAccPropList& fapl)
 {
     SUBTEST("DSetAccPropList::set/getChunkCache");
 
diff --git a/c++/test/h5cpputil.cpp b/c++/test/h5cpputil.cpp
index e38b34ad936..564c678e9ec 100644
--- a/c++/test/h5cpputil.cpp
+++ b/c++/test/h5cpputil.cpp
@@ -216,7 +216,7 @@ InvalidActionException::InvalidActionException() : Exception() {}
 //              func    - IN: Name of the function where failure should occur
 //              message - IN: Message
 //--------------------------------------------------------------------------
-InvalidActionException::InvalidActionException(const H5std_string func, const H5std_string message)
+InvalidActionException::InvalidActionException(const H5std_string& func, const H5std_string& message)
     : Exception(func, message)
 {
 }
@@ -241,7 +241,7 @@ TestFailedException::TestFailedException() : Exception() {}
 //              func    - IN: Name of the function where failure should occur
 //              message - IN: Message
 //--------------------------------------------------------------------------
-TestFailedException::TestFailedException(const H5std_string func, const H5std_string message)
+TestFailedException::TestFailedException(const H5std_string& func, const H5std_string& message)
     : Exception(func, message)
 {
 }
diff --git a/c++/test/h5cpputil.h b/c++/test/h5cpputil.h
index 4439ae3f661..266847a1278 100644
--- a/c++/test/h5cpputil.h
+++ b/c++/test/h5cpputil.h
@@ -48,14 +48,14 @@ void issue_fail_msg(const char *where, int line, const char *file_name, const ch
 
 class InvalidActionException : public Exception {
   public:
-    InvalidActionException(const H5std_string func_name, const H5std_string message = DEFAULT_MSG);
+    InvalidActionException(const H5std_string& func_name, const H5std_string& message = DEFAULT_MSG);
     InvalidActionException();
     virtual ~InvalidActionException() throw();
 };
 
 class TestFailedException : public Exception {
   public:
-    TestFailedException(const H5std_string func_name, const H5std_string message = DEFAULT_MSG);
+    TestFailedException(const H5std_string& func_name, const H5std_string& message = DEFAULT_MSG);
     TestFailedException();
     virtual ~TestFailedException() throw();
 };