diff --git a/devtools/shared/specs/targets/addon.js b/devtools/shared/specs/targets/addon.js
index 9c2cfd49ccc8..e71072c3dc34 100644
--- a/devtools/shared/specs/targets/addon.js
+++ b/devtools/shared/specs/targets/addon.js
@@ -36,7 +36,7 @@ const addonTargetSpec = generateActorSpec({
     // actor (bug 1269919), but as we may still connect to older servers which still do,
     // we have to keep it being mentioned here. Otherwise the event is considered as a
     // response to a request and confuses the packet ordering.
-    // We can remove that once FF57 is no longer supported.
+    // We can remove that once FF66 is no longer supported.
     newSource: {
       type: "newSource",
     },
diff --git a/devtools/shared/specs/targets/browsing-context.js b/devtools/shared/specs/targets/browsing-context.js
index 9848aaf2e42b..be4d43b21537 100644
--- a/devtools/shared/specs/targets/browsing-context.js
+++ b/devtools/shared/specs/targets/browsing-context.js
@@ -141,7 +141,7 @@ const browsingContextTargetSpecPrototype = {
     // actor (bug 1269919), but as we may still connect to older servers which still do,
     // we have to keep it being mentioned here. Otherwise the event is considered as a
     // response to a request and confuses the packet ordering.
-    // We can remove that once FF57 is no longer supported.
+    // We can remove that once FF66 is no longer supported.
     newSource: {
       type: "newSource",
     },
diff --git a/devtools/shared/specs/targets/content-process.js b/devtools/shared/specs/targets/content-process.js
index 7484e2a0524e..aa95dd5db38e 100644
--- a/devtools/shared/specs/targets/content-process.js
+++ b/devtools/shared/specs/targets/content-process.js
@@ -29,7 +29,7 @@ const contentProcessTargetSpec = generateActorSpec({
     // actor (bug 1269919), but as we may still connect to older servers which still do,
     // we have to keep it being mentioned here. Otherwise the event is considered as a
     // response to a request and confuses the packet ordering.
-    // We can remove that once FF57 is no longer supported.
+    // We can remove that once FF66 is no longer supported.
     newSource: {
       type: "newSource",
     },
diff --git a/devtools/shared/specs/targets/worker.js b/devtools/shared/specs/targets/worker.js
index e970f579d51c..42ff45a86f1d 100644
--- a/devtools/shared/specs/targets/worker.js
+++ b/devtools/shared/specs/targets/worker.js
@@ -41,7 +41,7 @@ const workerTargetSpec = generateActorSpec({
     // actor (bug 1269919), but as we may still connect to older servers which still do,
     // we have to keep it being mentioned here. Otherwise the event is considered as a
     // response to a request and confuses the packet ordering.
-    // We can remove that once FF57 is no longer supported.
+    // We can remove that once FF66 is no longer supported.
     newSource: {
       type: "newSource",
     },