diff --git a/src/cbmc/cbmc_parse_options.cpp b/src/cbmc/cbmc_parse_options.cpp
index 5ad4f8232fe..b83459fbd7c 100644
--- a/src/cbmc/cbmc_parse_options.cpp
+++ b/src/cbmc/cbmc_parse_options.cpp
@@ -434,7 +434,7 @@ int cbmc_parse_optionst::doit()
     return 6; // should contemplate EX_SOFTWARE from sysexits.h
   }
 
-  catch(const std::string error_msg)
+  catch(const std::string &error_msg)
   {
     error() << error_msg << eom;
     return 6; // should contemplate EX_SOFTWARE from sysexits.h
@@ -586,7 +586,7 @@ bool cbmc_parse_optionst::set_properties()
     return true;
   }
 
-  catch(const std::string e)
+  catch(const std::string &e)
   {
     error() << e << eom;
     return true;
@@ -648,7 +648,7 @@ int cbmc_parse_optionst::get_goto_program(
     return 6;
   }
 
-  catch(const std::string e)
+  catch(const std::string &e)
   {
     error() << e << eom;
     return 6;
@@ -708,7 +708,7 @@ void cbmc_parse_optionst::preprocessing()
     error() << e << eom;
   }
 
-  catch(const std::string e)
+  catch(const std::string &e)
   {
     error() << e << eom;
   }
@@ -840,7 +840,7 @@ bool cbmc_parse_optionst::process_goto_program(
     return true;
   }
 
-  catch(const std::string e)
+  catch(const std::string &e)
   {
     error() << e << eom;
     return true;
diff --git a/src/clobber/clobber_parse_options.cpp b/src/clobber/clobber_parse_options.cpp
index 9a687b32529..f3c35b6f8e4 100644
--- a/src/clobber/clobber_parse_options.cpp
+++ b/src/clobber/clobber_parse_options.cpp
@@ -154,7 +154,7 @@ int clobber_parse_optionst::doit()
     return 0;
   }
 
-  catch(const std::string error_msg)
+  catch(const std::string &error_msg)
   {
     error() << error_msg << messaget::eom;
     return 8;
diff --git a/src/goto-analyzer/goto_analyzer_parse_options.cpp b/src/goto-analyzer/goto_analyzer_parse_options.cpp
index 34fd8c8d0ad..54ed0ab5408 100644
--- a/src/goto-analyzer/goto_analyzer_parse_options.cpp
+++ b/src/goto-analyzer/goto_analyzer_parse_options.cpp
@@ -321,7 +321,7 @@ bool goto_analyzer_parse_optionst::set_properties()
     return true;
   }
 
-  catch(const std::string e)
+  catch(const std::string &e)
   {
     error() << e << eom;
     return true;
@@ -403,7 +403,7 @@ bool goto_analyzer_parse_optionst::process_goto_program(
     return true;
   }
 
-  catch(const std::string e)
+  catch(const std::string &e)
   {
     error() << e << eom;
     return true;
diff --git a/src/goto-cc/goto_cc_mode.cpp b/src/goto-cc/goto_cc_mode.cpp
index 483f3340967..b6802103f30 100644
--- a/src/goto-cc/goto_cc_mode.cpp
+++ b/src/goto-cc/goto_cc_mode.cpp
@@ -88,7 +88,7 @@ int goto_cc_modet::main(int argc, const char **argv)
     return EX_SOFTWARE;
   }
 
-  catch(const std::string e)
+  catch(const std::string &e)
   {
     error() << e << eom;
     return EX_SOFTWARE;
diff --git a/src/goto-diff/goto_diff_parse_options.cpp b/src/goto-diff/goto_diff_parse_options.cpp
index dc3ebca4c71..d439f1b9aa0 100644
--- a/src/goto-diff/goto_diff_parse_options.cpp
+++ b/src/goto-diff/goto_diff_parse_options.cpp
@@ -449,7 +449,7 @@ bool goto_diff_parse_optionst::process_goto_program(
     return true;
   }
 
-  catch(const std::string e)
+  catch(const std::string &e)
   {
     error() << e << eom;
     return true;
diff --git a/src/goto-instrument/goto_instrument_parse_options.cpp b/src/goto-instrument/goto_instrument_parse_options.cpp
index 65925406098..27f87141fd3 100644
--- a/src/goto-instrument/goto_instrument_parse_options.cpp
+++ b/src/goto-instrument/goto_instrument_parse_options.cpp
@@ -813,7 +813,7 @@ int goto_instrument_parse_optionst::doit()
     return 11;
   }
 
-  catch(const std::string e)
+  catch(const std::string &e)
   {
     error() << e << eom;
     return 11;
diff --git a/src/goto-programs/initialize_goto_model.cpp b/src/goto-programs/initialize_goto_model.cpp
index 5461c9015ee..1cdc67ef43f 100644
--- a/src/goto-programs/initialize_goto_model.cpp
+++ b/src/goto-programs/initialize_goto_model.cpp
@@ -184,7 +184,7 @@ bool initialize_goto_model(
     msg.error() << e << messaget::eom;
     return true;
   }
-  catch(const std::string e)
+  catch(const std::string &e)
   {
     msg.error() << e << messaget::eom;
     return true;
diff --git a/src/jbmc/jbmc_parse_options.cpp b/src/jbmc/jbmc_parse_options.cpp
index 9122c96cbd4..133e0aa3187 100644
--- a/src/jbmc/jbmc_parse_options.cpp
+++ b/src/jbmc/jbmc_parse_options.cpp
@@ -413,7 +413,7 @@ int jbmc_parse_optionst::doit()
     return 6; // should contemplate EX_SOFTWARE from sysexits.h
   }
 
-  catch(const std::string error_msg)
+  catch(const std::string &error_msg)
   {
     error() << error_msg << eom;
     return 6; // should contemplate EX_SOFTWARE from sysexits.h
@@ -546,7 +546,7 @@ bool jbmc_parse_optionst::set_properties()
     return true;
   }
 
-  catch(const std::string e)
+  catch(const std::string &e)
   {
     error() << e << eom;
     return true;
@@ -608,7 +608,7 @@ int jbmc_parse_optionst::get_goto_program(
     return 6;
   }
 
-  catch(const std::string e)
+  catch(const std::string &e)
   {
     error() << e << eom;
     return 6;
@@ -772,7 +772,7 @@ bool jbmc_parse_optionst::process_goto_program(
     return true;
   }
 
-  catch(const std::string e)
+  catch(const std::string &e)
   {
     error() << e << eom;
     return true;
diff --git a/src/memory-models/mmcc_parse_options.cpp b/src/memory-models/mmcc_parse_options.cpp
index 8fae9244839..03644ab95f5 100644
--- a/src/memory-models/mmcc_parse_options.cpp
+++ b/src/memory-models/mmcc_parse_options.cpp
@@ -64,7 +64,7 @@ int mmcc_parse_optionst::doit()
     std::cerr << error << '\n';
     return 10;
   }
-  catch(const std::string error)
+  catch(const std::string &error)
   {
     std::cerr << error << '\n';
     return 10;
diff --git a/unit/testing-utils/catch.hpp b/unit/testing-utils/catch.hpp
index 45328b8545c..511816748fa 100644
--- a/unit/testing-utils/catch.hpp
+++ b/unit/testing-utils/catch.hpp
@@ -7326,7 +7326,7 @@ namespace Catch {
             catch( std::exception& ex ) {
                 return ex.what();
             }
-            catch( std::string& msg ) {
+            catch(const std::string &msg) {
                 return msg;
             }
             catch( const char* msg ) {