diff --git a/include/jsoncons_ext/jsonschema/common/format_validator.hpp b/include/jsoncons_ext/jsonschema/common/format_validator.hpp
index 4d32f54e3..980385205 100644
--- a/include/jsoncons_ext/jsonschema/common/format_validator.hpp
+++ b/include/jsoncons_ext/jsonschema/common/format_validator.hpp
@@ -902,7 +902,7 @@ namespace jsonschema {
                 eval_path,
                 schema_location, 
                 instance_location, 
-                "\"" + value + "\" is not a RFC 3339 date string"));
+                "'" + value + "' is not a RFC 3339 date string."));
         }
     }
 
@@ -918,7 +918,7 @@ namespace jsonschema {
                 eval_path,
                 schema_location, 
                 instance_location, 
-                "\"" + value + "\" is not a RFC 3339 time string"));
+                "'" + value + "' is not a RFC 3339 time string."));
         }
     }
 
@@ -934,7 +934,7 @@ namespace jsonschema {
                 eval_path,  
                 schema_location,
                 instance_location, 
-                "\"" + value + "\" is not a RFC 3339 date-time string"));
+                "'" + value + "' is not a RFC 3339 date-time string."));
         }
     }
 
@@ -950,7 +950,7 @@ namespace jsonschema {
                 eval_path, 
                 schema_location, 
                 instance_location, 
-                "\"" + value + "\" is not a valid email address as defined by RFC 5322"));
+                "'" + value + "' is not a valid email address as defined by RFC 5322."));
         }
     } 
 
@@ -966,7 +966,7 @@ namespace jsonschema {
                 eval_path, 
                 schema_location, 
                 instance_location, 
-                "\"" + value + "\" is not a valid hostname as defined by RFC 3986 Appendix A"));
+                "'" + value + "' is not a valid hostname as defined by RFC 3986 Appendix A."));
         }
     } 
 
@@ -982,7 +982,7 @@ namespace jsonschema {
                 eval_path, 
                 schema_location, 
                 instance_location, 
-                "\"" + value + "\" is not a valid IPv4 address as defined by RFC 2673"));
+                "'" + value + "' is not a valid IPv4 address as defined by RFC 2673."));
         }
     } 
 
@@ -998,7 +998,7 @@ namespace jsonschema {
                 eval_path, 
                 schema_location, 
                 instance_location, 
-                "\"" + value + "\" is not a valid IPv6 address as defined by RFC 2373"));
+                "'" + value + "' is not a valid IPv6 address as defined by RFC 2373."));
         }
     } 
 
@@ -1019,7 +1019,7 @@ namespace jsonschema {
                 eval_path, 
                 schema_location, 
                 instance_location, 
-                "\"" + value + "\" is not a valid ECMAScript regular expression. " + e.what()));
+                "'" + value + "' is not a valid ECMAScript regular expression. " + e.what()));
         }
 #endif
     } 
diff --git a/include/jsoncons_ext/jsonschema/common/keyword_validators.hpp b/include/jsoncons_ext/jsonschema/common/keyword_validators.hpp
index 783882539..db0e63b01 100644
--- a/include/jsoncons_ext/jsonschema/common/keyword_validators.hpp
+++ b/include/jsoncons_ext/jsonschema/common/keyword_validators.hpp
@@ -363,11 +363,11 @@ namespace jsonschema {
             auto s = instance.template as<std::string>();
             if (!std::regex_search(s, regex_))
             {
-                std::string message("String \"");
+                std::string message("String '");
                 message.append(s);
-                message.append("\" does not match pattern \"");
+                message.append("' does not match pattern '");
                 message.append(pattern_string_);
-                message.append("\"");
+                message.append("'.");
                 reporter.error(validation_message(this->keyword_name(),
                     this_context.eval_path(), 
                     this->schema_location(),
@@ -1303,7 +1303,7 @@ namespace jsonschema {
                                                          this_context.eval_path(),
                                                          this->schema_location(),
                                                          instance_location,
-                                                         "Required property \"" + key + "\" not found"));
+                                                         "Required property '" + key + "' not found."));
                         if(reporter.fail_early())
                     {
                             return;
@@ -1510,7 +1510,7 @@ namespace jsonschema {
                     this_context.eval_path(), 
                     this->schema_location(), 
                     instance_location, 
-                    instance.template as<std::string>() + " is not a valid enum value"));
+                    "'" + instance.template as<std::string>() + "' is not a valid enum value."));
                 if (reporter.fail_early())
                 {
                     return;
@@ -1994,7 +1994,7 @@ namespace jsonschema {
                                 prop_context.eval_path(), 
                                 this->schema_location(), 
                                 prop_location,
-                                "Additional property '" + prop.key() + "' but the schema does not allow additional properties."));
+                                "Additional property '" + prop.key() + "' not allowed by schema."));
                             break;
                         }
                     }
@@ -2033,7 +2033,7 @@ namespace jsonschema {
                                     this_context.eval_path(), 
                                     additional_properties_->schema_location().string(),
                                     instance_location, 
-                                    "Additional property \"" + prop.key() + "\" found but was invalid."));
+                                    "Additional property '" + prop.key() + "' found but was invalid."));
                                 if (reporter.fail_early())
                                 {
                                     return;
@@ -2396,7 +2396,7 @@ namespace jsonschema {
                     this_context.eval_path(), 
                     this->schema_location(), 
                     instance_location, 
-                    "Expected at least one array item to match \"contains\" schema", 
+                    "Expected at least one array item to match 'contains' schema.",
                     local_reporter.errors));
                 if (reporter.fail_early())
                 {
diff --git a/test/jsonschema/src/validation_report_tests.cpp b/test/jsonschema/src/validation_report_tests.cpp
index d070f9528..22ab769c9 100644
--- a/test/jsonschema/src/validation_report_tests.cpp
+++ b/test/jsonschema/src/validation_report_tests.cpp
@@ -177,7 +177,7 @@ TEST_CASE("jsonschema additionalProperties output tests")
         "evaluationPath": "/additionalProperties/direction",
         "schemaLocation": "#",
         "instanceLocation": "/direction",
-        "error": "Additional property 'direction' but the schema does not allow additional properties."
+        "error": "Additional property 'direction' not allowed by schema."
     }
 ]
         )");