diff --git a/common/changes/@microsoft/rush/fix-look-by-path_2023-04-25-09-41.json b/common/changes/@microsoft/rush/fix-look-by-path_2023-04-25-09-41.json
new file mode 100644
index 00000000000..d5b4c94712a
--- /dev/null
+++ b/common/changes/@microsoft/rush/fix-look-by-path_2023-04-25-09-41.json
@@ -0,0 +1,10 @@
+{
+  "changes": [
+    {
+      "packageName": "@microsoft/rush",
+      "comment": "Fix an issue where the last character in a project's path is ignored when determining which files contribute to the project's cache ID.",
+      "type": "none"
+    }
+  ],
+  "packageName": "@microsoft/rush"
+}
\ No newline at end of file
diff --git a/libraries/rush-lib/src/logic/LookupByPath.ts b/libraries/rush-lib/src/logic/LookupByPath.ts
index a848949f216..ce209f909e4 100644
--- a/libraries/rush-lib/src/logic/LookupByPath.ts
+++ b/libraries/rush-lib/src/logic/LookupByPath.ts
@@ -111,7 +111,7 @@ export class LookupByPath<TItem> {
     }
 
     // Last segment
-    if (previousIndex + 1 < input.length) {
+    if (previousIndex < input.length) {
       yield {
         prefix: input.slice(previousIndex, input.length),
         index: input.length
diff --git a/libraries/rush-lib/src/logic/test/LookupByPath.test.ts b/libraries/rush-lib/src/logic/test/LookupByPath.test.ts
index 5b4cbeed881..2d56d082d58 100644
--- a/libraries/rush-lib/src/logic/test/LookupByPath.test.ts
+++ b/libraries/rush-lib/src/logic/test/LookupByPath.test.ts
@@ -20,6 +20,10 @@ describe(LookupByPath.iteratePathSegments.name, () => {
     const result = [...LookupByPath.iteratePathSegments('foo/bar/baz')];
     expect(result).toEqual(['foo', 'bar', 'baz']);
   });
+  it('returns correct last single character segment', () => {
+    const result = [...LookupByPath.iteratePathSegments('foo/a')];
+    expect(result).toEqual(['foo', 'a']);
+  });
 });
 
 describe(LookupByPath.prototype.findChildPath.name, () => {