diff --git a/projects/SelfTest/Baselines/compact.sw.approved.txt b/projects/SelfTest/Baselines/compact.sw.approved.txt
index 3e2984f6..fccf52ca 100644
--- a/projects/SelfTest/Baselines/compact.sw.approved.txt
+++ b/projects/SelfTest/Baselines/compact.sw.approved.txt
@@ -1031,6 +1031,7 @@ String.tests.cpp:<line number>: passed: ss.size() == 6 for: 6 == 6
 String.tests.cpp:<line number>: passed: std::strcmp( ss.c_str(), "world!" ) == 0 for: 0 == 0
 String.tests.cpp:<line number>: passed: s.c_str() == s2.c_str() for: "hello world!" == "hello world!"
 String.tests.cpp:<line number>: passed: s.c_str() != ss.c_str() for: "hello world!" != "hello"
+String.tests.cpp:<line number>: passed: s.substr(s.size() + 1, 123).empty() for: true
 String.tests.cpp:<line number>: passed: StringRef("hello") == StringRef("hello") for: hello == hello
 String.tests.cpp:<line number>: passed: StringRef("hello") != StringRef("cello") for: hello != cello
 String.tests.cpp:<line number>: passed: sr == "a standard string" for: a standard string == "a standard string"
diff --git a/projects/SelfTest/Baselines/console.std.approved.txt b/projects/SelfTest/Baselines/console.std.approved.txt
index 1f30e8f4..a52bb9a5 100644
--- a/projects/SelfTest/Baselines/console.std.approved.txt
+++ b/projects/SelfTest/Baselines/console.std.approved.txt
@@ -1381,5 +1381,5 @@ due to unexpected exception with message:
 
 ===============================================================================
 test cases:  300 |  226 passed |  70 failed |  4 failed as expected
-assertions: 1557 | 1405 passed | 131 failed | 21 failed as expected
+assertions: 1558 | 1406 passed | 131 failed | 21 failed as expected
 
diff --git a/projects/SelfTest/Baselines/console.sw.approved.txt b/projects/SelfTest/Baselines/console.sw.approved.txt
index 3bd3a759..1fca8cf3 100644
--- a/projects/SelfTest/Baselines/console.sw.approved.txt
+++ b/projects/SelfTest/Baselines/console.sw.approved.txt
@@ -7712,6 +7712,19 @@ String.tests.cpp:<line number>: PASSED:
 with expansion:
   "hello world!" != "hello"
 
+-------------------------------------------------------------------------------
+StringRef
+  Substrings
+  Past the end substring
+-------------------------------------------------------------------------------
+String.tests.cpp:<line number>
+...............................................................................
+
+String.tests.cpp:<line number>: PASSED:
+  REQUIRE( s.substr(s.size() + 1, 123).empty() )
+with expansion:
+  true
+
 -------------------------------------------------------------------------------
 StringRef
   Comparisons
@@ -12444,5 +12457,5 @@ Misc.tests.cpp:<line number>: PASSED:
 
 ===============================================================================
 test cases:  300 |  210 passed |  86 failed |  4 failed as expected
-assertions: 1574 | 1405 passed | 148 failed | 21 failed as expected
+assertions: 1575 | 1406 passed | 148 failed | 21 failed as expected
 
diff --git a/projects/SelfTest/Baselines/junit.sw.approved.txt b/projects/SelfTest/Baselines/junit.sw.approved.txt
index c3cf2d6f..ca1998ed 100644
--- a/projects/SelfTest/Baselines/junit.sw.approved.txt
+++ b/projects/SelfTest/Baselines/junit.sw.approved.txt
@@ -1,7 +1,7 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <testsuitesloose text artifact
 >
-  <testsuite name="<exe-name>" errors="17" failures="132" tests="1575" hostname="tbd" time="{duration}" timestamp="{iso8601-timestamp}">
+  <testsuite name="<exe-name>" errors="17" failures="132" tests="1576" hostname="tbd" time="{duration}" timestamp="{iso8601-timestamp}">
     <properties>
       <property name="filters" value="~[!nonportable]~[!benchmark]~[approvals]"/>
       <property name="random-seed" value="1"/>
@@ -722,6 +722,7 @@ Matchers.tests.cpp:<line number>
     <testcase classname="<exe-name>.global" name="StringRef/Substrings/non-zero-based substring" time="{duration}"/>
     <testcase classname="<exe-name>.global" name="StringRef/Substrings/Pointer values of full refs should match" time="{duration}"/>
     <testcase classname="<exe-name>.global" name="StringRef/Substrings/Pointer values of substring refs should not match" time="{duration}"/>
+    <testcase classname="<exe-name>.global" name="StringRef/Substrings/Past the end substring" time="{duration}"/>
     <testcase classname="<exe-name>.global" name="StringRef/Comparisons" time="{duration}"/>
     <testcase classname="<exe-name>.global" name="StringRef/from std::string/implicitly constructed" time="{duration}"/>
     <testcase classname="<exe-name>.global" name="StringRef/from std::string/explicitly constructed" time="{duration}"/>
diff --git a/projects/SelfTest/Baselines/xml.sw.approved.txt b/projects/SelfTest/Baselines/xml.sw.approved.txt
index de3b7657..c406d061 100644
--- a/projects/SelfTest/Baselines/xml.sw.approved.txt
+++ b/projects/SelfTest/Baselines/xml.sw.approved.txt
@@ -9516,6 +9516,20 @@ Message from section two
         </Section>
         <OverallResults successes="1" failures="0" expectedFailures="0"/>
       </Section>
+      <Section name="Substrings" filename="projects/<exe-name>/IntrospectiveTests/String.tests.cpp" >
+        <Section name="Past the end substring" filename="projects/<exe-name>/IntrospectiveTests/String.tests.cpp" >
+          <Expression success="true" type="REQUIRE" filename="projects/<exe-name>/IntrospectiveTests/String.tests.cpp" >
+            <Original>
+              s.substr(s.size() + 1, 123).empty()
+            </Original>
+            <Expanded>
+              true
+            </Expanded>
+          </Expression>
+          <OverallResults successes="1" failures="0" expectedFailures="0"/>
+        </Section>
+        <OverallResults successes="1" failures="0" expectedFailures="0"/>
+      </Section>
       <Section name="Comparisons" filename="projects/<exe-name>/IntrospectiveTests/String.tests.cpp" >
         <Expression success="true" type="REQUIRE" filename="projects/<exe-name>/IntrospectiveTests/String.tests.cpp" >
           <Original>
@@ -14812,7 +14826,7 @@ loose text artifact
       </Section>
       <OverallResult success="true"/>
     </TestCase>
-    <OverallResults successes="1405" failures="149" expectedFailures="21"/>
+    <OverallResults successes="1406" failures="149" expectedFailures="21"/>
   </Group>
-  <OverallResults successes="1405" failures="148" expectedFailures="21"/>
+  <OverallResults successes="1406" failures="148" expectedFailures="21"/>
 </Catch>
diff --git a/projects/SelfTest/IntrospectiveTests/String.tests.cpp b/projects/SelfTest/IntrospectiveTests/String.tests.cpp
index 77c16dcb..456dd4a7 100644
--- a/projects/SelfTest/IntrospectiveTests/String.tests.cpp
+++ b/projects/SelfTest/IntrospectiveTests/String.tests.cpp
@@ -111,6 +111,10 @@ TEST_CASE( "StringRef", "[Strings][StringRef]" ) {
         SECTION( "Pointer values of substring refs should not match" ) {
             REQUIRE( s.c_str() != ss.c_str() );
         }
+
+        SECTION("Past the end substring") {
+            REQUIRE(s.substr(s.size() + 1, 123).empty());
+        }
     }
 
     SECTION( "Comparisons" ) {