diff --git a/dom/base/test/test_find.html b/dom/base/test/test_find.html
index 9969d744ada7..32a18773f3e3 100644
--- a/dom/base/test/test_find.html
+++ b/dom/base/test/test_find.html
@@ -6,7 +6,9 @@
 <script>
 const t = async_test("Test window.find / nsFind");
 
-function testFindable(isFindable, textToFind, buildDoc, description) {
+function testFindable(findCount, textToFind, buildDoc, description) {
+  if (typeof findCount == "boolean")
+    findCount = findCount ? 1 : 0;
   try {
     const iframe = document.querySelector("iframe")
     iframe.contentDocument.documentElement.innerHTML =
@@ -16,11 +18,15 @@ function testFindable(isFindable, textToFind, buildDoc, description) {
       buildDoc(iframe.contentDocument);
 
     iframe.contentWindow.getSelection().removeAllRanges();
-    assert_equals(
-      isFindable,
-      iframe.contentWindow.find(textToFind),
-      "Should be " + (isFindable ? "" : "not ") + "findable: " + description + ", text: " + textToFind
-    );
+    for (let i = findCount; i >= 0; --i) {
+      const expectFindable = i != 0;
+      assert_equals(
+        iframe.contentWindow.find(textToFind),
+        expectFindable,
+        "Should be " + (expectFindable ? "" : "not ") + "findable: " + description + ", text: " + textToFind + ", iter: " + (findCount - i + 1)
+      );
+    }
+
   } catch (ex) {
     assert_unreached(ex);
   }
@@ -178,6 +184,8 @@ let runTests = t.step_func_done(function() {
   testFindable(true, "history.kafka", `
     <code>database.history&#8203;.kafka.bootstrap.servers</code>
   `, "ZWSP should be ignored");
+
+  testFindable(2, " ", "a    b    c", "Collapsed whitespace");
 });
 
 window.onload = function() {
diff --git a/toolkit/components/find/nsFind.cpp b/toolkit/components/find/nsFind.cpp
index f9e3d1fc06b0..d7d5a18fab96 100644
--- a/toolkit/components/find/nsFind.cpp
+++ b/toolkit/components/find/nsFind.cpp
@@ -881,16 +881,17 @@ nsFind::Find(const nsAString& aPatText, nsRange* aSearchRange,
 
         // Make the range:
         // Check for word break (if necessary)
-        if (mWordBreaker) {
+        if (mWordBreaker || inWhitespace) {
           int32_t nextfindex = findex + incr;
 
           char16_t nextChar;
           // If still in array boundaries, get nextChar.
           if (mFindBackward ? (nextfindex >= 0) : (nextfindex < fragLen)) {
-            if (t2b)
+            if (t2b) {
               nextChar = DecodeChar(t2b, &nextfindex);
-            else
+            } else {
               nextChar = CHAR_TO_UNICHAR(t1b[nextfindex]);
+            }
           } else {
             // Get next character from the next node.
             nextChar = PeekNextChar(state, !!matchAnchorNode);
@@ -901,10 +902,16 @@ nsFind::Find(const nsAString& aPatText, nsRange* aSearchRange,
           }
 
           // If a word break isn't there when it needs to be, reset search.
-          if (!BreakInBetween(c, nextChar)) {
+          if (mWordBreaker && !BreakInBetween(c, nextChar)) {
             matchAnchorNode = nullptr;
             continue;
           }
+
+          if (inWhitespace && IsSpace(nextChar)) {
+            // If the next character is also an space, keep going, this space
+            // will collapse.
+            continue;
+          }
         }
 
         int32_t matchStartOffset;