diff --git a/packages/smithy-client/src/split-header.spec.ts b/packages/smithy-client/src/split-header.spec.ts
index fd6933fc5fc..608abf76a06 100644
--- a/packages/smithy-client/src/split-header.spec.ts
+++ b/packages/smithy-client/src/split-header.spec.ts
@@ -7,9 +7,16 @@ describe(splitHeader.name, () => {
     expect(splitHeader("a, b, c")).toEqual(["a", "b", "c"]);
     expect(splitHeader("a , b , c")).toEqual(["a", "b", "c"]);
     expect(splitHeader(`a , b , "  c  "`)).toEqual(["a", "b", "  c  "]);
+    expect(splitHeader(`  a  ,     , b`)).toEqual(["a", "", "b"]);
+    expect(splitHeader(`,,`)).toEqual(["", "", ""]);
+    expect(splitHeader(`    ,    ,    `)).toEqual(["", "", ""]);
   });
   it("should split a string by commas that are not in quotes, and remove outer quotes", () => {
     expect(splitHeader('"b,c", "\\"def\\"", a')).toEqual(["b,c", '"def"', "a"]);
     expect(splitHeader('"a,b,c", ""def"", "a,b ,c"')).toEqual(["a,b,c", '"def"', "a,b ,c"]);
+    expect(splitHeader(`""`)).toEqual([``]);
+    expect(splitHeader(``)).toEqual([``]);
+    expect(splitHeader(`\\"`)).toEqual([`"`]);
+    expect(splitHeader(`"`)).toEqual([`"`]);
   });
 });
diff --git a/packages/smithy-client/src/split-header.ts b/packages/smithy-client/src/split-header.ts
index da61b573b59..e76aa577de6 100644
--- a/packages/smithy-client/src/split-header.ts
+++ b/packages/smithy-client/src/split-header.ts
@@ -34,6 +34,9 @@ export const splitHeader = (value: string): string[] => {
   return values.map((v) => {
     v = v.trim();
     const z = v.length;
+    if (z < 2) {
+      return v;
+    }
     if (v[0] === `"` && v[z - 1] === `"`) {
       v = v.slice(1, z - 1);
     }