diff --git a/src/client/sse.test.ts b/src/client/sse.test.ts
index 2b166530..d2bf5911 100644
--- a/src/client/sse.test.ts
+++ b/src/client/sse.test.ts
@@ -24,7 +24,7 @@ describe("SSEClientTransport", () => {
       // Send SSE headers
       res.writeHead(200, {
         "Content-Type": "text/event-stream",
-        "Cache-Control": "no-cache",
+        "Cache-Control": "no-cache, no-transform",
         Connection: "keep-alive",
       });
 
@@ -183,7 +183,7 @@ describe("SSEClientTransport", () => {
         if (req.method === "GET") {
           res.writeHead(200, {
             "Content-Type": "text/event-stream",
-            "Cache-Control": "no-cache",
+            "Cache-Control": "no-cache, no-transform",
             Connection: "keep-alive",
           });
           res.write("event: endpoint\n");
@@ -397,7 +397,7 @@ describe("SSEClientTransport", () => {
 
             res.writeHead(200, {
               "Content-Type": "text/event-stream",
-              "Cache-Control": "no-cache",
+              "Cache-Control": "no-cache, no-transform",
               Connection: "keep-alive",
             });
             res.write("event: endpoint\n");
@@ -524,7 +524,7 @@ describe("SSEClientTransport", () => {
         if (auth === "Bearer new-token") {
           res.writeHead(200, {
             "Content-Type": "text/event-stream",
-            "Cache-Control": "no-cache",
+            "Cache-Control": "no-cache, no-transform",
             Connection: "keep-alive",
           });
           res.write("event: endpoint\n");
@@ -610,7 +610,7 @@ describe("SSEClientTransport", () => {
 
             res.writeHead(200, {
               "Content-Type": "text/event-stream",
-              "Cache-Control": "no-cache",
+              "Cache-Control": "no-cache, no-transform",
               Connection: "keep-alive",
             });
             res.write("event: endpoint\n");
diff --git a/src/server/sse.ts b/src/server/sse.ts
index 84c1cbb9..e6cddc4e 100644
--- a/src/server/sse.ts
+++ b/src/server/sse.ts
@@ -44,7 +44,7 @@ export class SSEServerTransport implements Transport {
 
     this.res.writeHead(200, {
       "Content-Type": "text/event-stream",
-      "Cache-Control": "no-cache",
+      "Cache-Control": "no-cache, no-transform",
       Connection: "keep-alive",
     });