diff --git a/js/src/jsscript.cpp b/js/src/jsscript.cpp
index ec62710c357a..3e89b6da6603 100644
--- a/js/src/jsscript.cpp
+++ b/js/src/jsscript.cpp
@@ -1884,8 +1884,8 @@ ScriptSource::sourceText(JSContext* cx)
                 return mozilla::Nothing();
             }
 
-            if (!DecompressString((const unsigned char*) ss.compressedData(),
-                                  ss.compressedBytes(),
+            if (!DecompressString((const unsigned char*) c.raw.chars(),
+                                  c.raw.length(),
                                   reinterpret_cast<unsigned char*>(decompressed.get()),
                                   lengthWithNull * sizeof(char16_t)))
             {
@@ -2051,6 +2051,8 @@ ScriptSource::setSourceCopy(ExclusiveContext* cx, SourceBufferHolder& srcBuf,
 SourceCompressionTask::ResultType
 SourceCompressionTask::work()
 {
+    MOZ_ASSERT(ss->data.is<ScriptSource::Uncompressed>());
+
     // Try to keep the maximum memory usage down by only allocating half the
     // size of the string, first.
     size_t inputBytes = ss->length() * sizeof(char16_t);
@@ -2059,7 +2061,9 @@ SourceCompressionTask::work()
     if (!compressed)
         return OOM;
 
-    Compressor comp(reinterpret_cast<const unsigned char*>(ss->uncompressedChars()), inputBytes);
+    const char16_t* chars = ss->data.as<ScriptSource::Uncompressed>().string.chars();
+    Compressor comp(reinterpret_cast<const unsigned char*>(chars),
+                    inputBytes);
     if (!comp.init())
         return OOM;
 
@@ -2127,7 +2131,7 @@ ScriptSource::performXDR(XDRState<mode>* xdr)
         }
 
         ReturnType match(Compressed& c) {
-            return c.nbytes();
+            return c.raw.length();
         }
 
         ReturnType match(Missing&) {
diff --git a/js/src/jsscript.h b/js/src/jsscript.h
index 76bdc5ba4109..cf7caef48e73 100644
--- a/js/src/jsscript.h
+++ b/js/src/jsscript.h
@@ -620,14 +620,12 @@ class ScriptSource
     struct Compressed
     {
         SharedImmutableString raw;
-        size_t length;
+        size_t uncompressedLength;
 
-        Compressed(SharedImmutableString&& raw, size_t length)
+        Compressed(SharedImmutableString&& raw, size_t uncompressedLength)
           : raw(mozilla::Move(raw))
-          , length(length)
+          , uncompressedLength(uncompressedLength)
         { }
-
-        size_t nbytes() const { return raw.length(); }
     };
 
     using SourceType = mozilla::Variant<Missing, Uncompressed, Compressed>;
@@ -724,7 +722,7 @@ class ScriptSource
             }
 
             ReturnType match(const Compressed& c) {
-                return c.length;
+                return c.uncompressedLength;
             }
 
             ReturnType match(const Missing& m) {
@@ -751,18 +749,6 @@ class ScriptSource
     void addSizeOfIncludingThis(mozilla::MallocSizeOf mallocSizeOf,
                                 JS::ScriptSourceInfo* info) const;
 
-    const char16_t* uncompressedChars() const {
-        return data.as<Uncompressed>().string.chars();
-    }
-
-    const void* compressedData() const {
-        return static_cast<const void*>(data.as<Compressed>().raw.chars());
-    }
-
-    size_t compressedBytes() const {
-        return data.as<Compressed>().nbytes();
-    }
-
     MOZ_MUST_USE bool setSource(ExclusiveContext* cx,
                                 mozilla::UniquePtr<char16_t[], JS::FreePolicy>&& source,
                                 size_t length);