diff --git a/src/keygen/dell.spec.ts b/src/keygen/dell.spec.ts
index 63fa823..25cbc4c 100644
--- a/src/keygen/dell.spec.ts
+++ b/src/keygen/dell.spec.ts
@@ -310,6 +310,11 @@ describe("Test Dell BIOS", () => {
     it("Dell for: 1234567-1F66", () => {
         expect(dellSolver("1234567-1f66")).toEqual(["kIpTBzx0m3s10JDR"]);
     });
+    it("Dell for: 123456a-1F66", () => {
+        // AFAIK Dell service tags is always uppercase
+        // so this supposed to calculate password for 123456A-1F66
+        expect(dellSolver("123456a-1f66")).toEqual(["5sS11TUKBmBOQKRS"]);
+    });
     it("Dell HDD for: 1234567890A-595B", () => {
         expect(dellHddSolver("1234567890A-595b")).toEqual(["nyoap4lq"]);
     });
@@ -336,5 +341,6 @@ describe("Latitude 3540", () => {
     });
     it("Dell Latitude 3540 Solver", () => {
         expect(dellLatitude3540Solver("5F3988D5E0ACE4BF-7QH8602")).toEqual(["98072364"]);
+        expect(dellLatitude3540Solver("5F3988D5E0ACE4bF-7QH8602")).toEqual(["98072364"]);
     });
 });
diff --git a/src/keygen/dell/index.ts b/src/keygen/dell/index.ts
index 67389b7..6f35d9d 100644
--- a/src/keygen/dell/index.ts
+++ b/src/keygen/dell/index.ts
@@ -257,8 +257,8 @@ export let dellSolver = makeSolver({
         }
     },
     fun: (password: string) => {
-        let suffix = password.slice(7, 11).toUpperCase();
-        return keygenDell(password.slice(0, 7), suffix as DellTag, SuffixType.ServiceTag);
+        const suffix = password.slice(7, 11).toUpperCase();
+        return keygenDell(password.slice(0, 7).toUpperCase(), suffix as DellTag, SuffixType.ServiceTag);
     }
 });
 
@@ -274,8 +274,8 @@ export let dellHddSolver = makeSolver({
         }
     },
     fun: (password: string) => {
-        let suffix = password.slice(11, 15).toUpperCase();
-        return keygenDell(password.slice(0, 11), suffix as DellTag, SuffixType.HDD);
+        const suffix = password.slice(11, 15).toUpperCase();
+        return keygenDell(password.slice(0, 11).toUpperCase(), suffix as DellTag, SuffixType.HDD);
     }
 });