diff --git a/accessible/tests/browser/e10s/browser.ini b/accessible/tests/browser/e10s/browser.ini
index 367b9d4eb8c0..d5ec521c54c9 100644
--- a/accessible/tests/browser/e10s/browser.ini
+++ b/accessible/tests/browser/e10s/browser.ini
@@ -14,12 +14,14 @@ support-files =
 
 # Caching tests
 [browser_caching_attributes.js]
+skip-if = fission # Bug 1556627
 [browser_caching_description.js]
 [browser_caching_name.js]
 skip-if = (os == "linux" && bits == 64) || (debug && os == "mac") || (debug && os == "win") #Bug 1388256
 [browser_caching_relations.js]
 [browser_caching_states.js]
 [browser_caching_value.js]
+skip-if = fission # Bug 1556627
 
 [browser_contentSelectDropdown.js]
 
diff --git a/accessible/tests/browser/e10s/browser_caching_attributes.js b/accessible/tests/browser/e10s/browser_caching_attributes.js
index fbdd4d2011d2..fb64398ba403 100644
--- a/accessible/tests/browser/e10s/browser_caching_attributes.js
+++ b/accessible/tests/browser/e10s/browser_caching_attributes.js
@@ -129,5 +129,6 @@ addAccessibleTask(
       testAttrs(textbox, expected);
       testAbsentAttrs(textbox, unexpected);
     }
-  }
+  },
+  { iframe: true }
 );
diff --git a/accessible/tests/browser/e10s/browser_caching_description.js b/accessible/tests/browser/e10s/browser_caching_description.js
index dd11708bccc4..e6b00a24dd25 100644
--- a/accessible/tests/browser/e10s/browser_caching_description.js
+++ b/accessible/tests/browser/e10s/browser_caching_description.js
@@ -43,7 +43,7 @@ const tests = [
         value: "aria description",
       },
     ],
-    waitFor: [[EVENT_REORDER, "body"]],
+    waitFor: [[EVENT_REORDER, matchContentDoc]],
     expected: "",
   },
   {
@@ -72,7 +72,7 @@ const tests = [
         value: "title",
       },
     ],
-    waitFor: [[EVENT_REORDER, "body"]],
+    waitFor: [[EVENT_REORDER, matchContentDoc]],
     expected: "another description",
   },
   {
@@ -108,7 +108,7 @@ const tests = [
         value: "aria description",
       },
     ],
-    waitFor: [[EVENT_REORDER, "body"]],
+    waitFor: [[EVENT_REORDER, matchContentDoc]],
     expected: "another description",
   },
   {
@@ -209,5 +209,6 @@ addAccessibleTask(
       }
       testDescr(imgAcc, expected);
     }
-  }
+  },
+  { iframe: true }
 );
diff --git a/accessible/tests/browser/e10s/browser_caching_name.js b/accessible/tests/browser/e10s/browser_caching_name.js
index f9634be65da6..ccb60688a91a 100644
--- a/accessible/tests/browser/e10s/browser_caching_name.js
+++ b/accessible/tests/browser/e10s/browser_caching_name.js
@@ -514,20 +514,24 @@ async function testNameRule(browser, target, ruleset, expected) {
 }
 
 markupTests.forEach(({ id, ruleset, markup, expected }) =>
-  addAccessibleTask(markup, async function(browser, accDoc) {
-    const observer = {
-      observe(subject, topic, data) {
-        const event = subject.QueryInterface(nsIAccessibleEvent);
-        console.log(eventToString(event));
-      },
-    };
-    Services.obs.addObserver(observer, "accessible-event");
-    // Find a target accessible from an accessible subtree.
-    let acc = findAccessibleChildByID(accDoc, id);
-    // Find target's parent accessible from an accessible subtree.
-    let parent = getAccessibleDOMNodeID(acc.parent);
-    let target = { id, parent, acc };
-    await testNameRule(browser, target, rules[ruleset], expected);
-    Services.obs.removeObserver(observer, "accessible-event");
-  })
+  addAccessibleTask(
+    markup,
+    async function(browser, accDoc) {
+      const observer = {
+        observe(subject, topic, data) {
+          const event = subject.QueryInterface(nsIAccessibleEvent);
+          console.log(eventToString(event));
+        },
+      };
+      Services.obs.addObserver(observer, "accessible-event");
+      // Find a target accessible from an accessible subtree.
+      let acc = findAccessibleChildByID(accDoc, id);
+      // Find target's parent accessible from an accessible subtree.
+      let parent = getAccessibleDOMNodeID(acc.parent);
+      let target = { id, parent, acc };
+      await testNameRule(browser, target, rules[ruleset], expected);
+      Services.obs.removeObserver(observer, "accessible-event");
+    },
+    { iframe: true }
+  )
 );
diff --git a/accessible/tests/browser/e10s/browser_caching_relations.js b/accessible/tests/browser/e10s/browser_caching_relations.js
index 743bd57d24ac..af7982046cc6 100644
--- a/accessible/tests/browser/e10s/browser_caching_relations.js
+++ b/accessible/tests/browser/e10s/browser_caching_relations.js
@@ -91,5 +91,6 @@ addAccessibleTask(
     for (let spec of attrRelationsSpec) {
       await testRelated(browser, accDoc, ...spec);
     }
-  }
+  },
+  { iframe: true }
 );
diff --git a/accessible/tests/browser/e10s/browser_caching_states.js b/accessible/tests/browser/e10s/browser_caching_states.js
index 2f4bd5252572..6ae6847fc371 100644
--- a/accessible/tests/browser/e10s/browser_caching_states.js
+++ b/accessible/tests/browser/e10s/browser_caching_states.js
@@ -149,5 +149,6 @@ addAccessibleTask(
     await runStateTests(browser, accDoc, "checkbox", attributeTests);
     await runStateTests(browser, accDoc, "file", ariaTests);
     await runStateTests(browser, accDoc, "text", extraStateTests);
-  }
+  },
+  { iframe: true }
 );
diff --git a/accessible/tests/browser/e10s/browser_caching_value.js b/accessible/tests/browser/e10s/browser_caching_value.js
index f465f8fe4ad8..b0e1e85a8f52 100644
--- a/accessible/tests/browser/e10s/browser_caching_value.js
+++ b/accessible/tests/browser/e10s/browser_caching_value.js
@@ -29,7 +29,13 @@ const valueTests = [
     id: "select",
     async action(browser) {
       await invokeFocus(browser, "select");
-      await BrowserTestUtils.synthesizeKey("3", {}, browser);
+      await invokeContentTask(browser, [], () => {
+        const { ContentTaskUtils } = ChromeUtils.import(
+          "resource://testing-common/ContentTaskUtils.jsm"
+        );
+        const EventUtils = ContentTaskUtils.getEventUtils(content);
+        EventUtils.synthesizeKey("3", {}, content);
+      });
     },
     waitFor: EVENT_TEXT_VALUE_CHANGE,
     expected: "3rd",
@@ -178,5 +184,6 @@ addAccessibleTask(
         is(acc.value, expected, `Correct value for ${prettyName(acc)}`);
       }
     }
-  }
+  },
+  { iframe: true }
 );