diff --git a/API/hermes/hermes.cpp b/API/hermes/hermes.cpp
index f7d4791c306..406c3c1a1b2 100644
--- a/API/hermes/hermes.cpp
+++ b/API/hermes/hermes.cpp
@@ -1197,15 +1197,25 @@ void HermesRuntime::setFatalHandler(void (*handler)(const std::string &)) {
 }
 
 namespace {
-// A class which adapts a jsi buffer to a Hermes buffer.
+
+/// A class which adapts a jsi buffer to a Hermes buffer.
+/// It also provides the ability to create a partial "view" into the buffer.
 class BufferAdapter final : public ::hermes::Buffer {
  public:
-  BufferAdapter(std::shared_ptr<const jsi::Buffer> buf) : buf_(std::move(buf)) {
-    data_ = buf_->data();
-    size_ = buf_->size();
+  explicit BufferAdapter(
+      const std::shared_ptr<const jsi::Buffer> &buf,
+      const uint8_t *data,
+      size_t size)
+      : buf_(buf) {
+    data_ = data;
+    size_ = size;
   }
 
+  explicit BufferAdapter(const std::shared_ptr<const jsi::Buffer> &buf)
+      : BufferAdapter(buf, buf->data(), buf->size()) {}
+
  private:
+  /// The buffer we are "adapting".
   std::shared_ptr<const jsi::Buffer> buf_;
 };
 } // namespace
@@ -1420,6 +1430,28 @@ class HermesPreparedJavaScript final : public jsi::PreparedJavaScript {
   }
 };
 
+#ifndef HERMESVM_LEAN
+
+/// If the buffer contains an embedded terminating zero, shrink it, so it is
+/// one past the size, as per the LLVM MemoryBuffer convention. Otherwise, copy
+/// it into a new zero-terminated buffer.
+std::unique_ptr<BufferAdapter> ensureZeroTerminated(
+    const std::shared_ptr<const jsi::Buffer> &buf) {
+  size_t size = buf->size();
+  const uint8_t *data = buf->data();
+
+  // Check for zero termination
+  if (size != 0 && data[size - 1] == 0) {
+    return std::make_unique<BufferAdapter>(buf, data, size - 1);
+  } else {
+    // Copy into a zero-terminated instance.
+    return std::make_unique<BufferAdapter>(std::make_shared<jsi::StringBuffer>(
+        std::string((const char *)data, size)));
+  }
+}
+
+#endif
+
 } // namespace
 
 std::shared_ptr<const jsi::PreparedJavaScript>
@@ -1428,11 +1460,10 @@ HermesRuntimeImpl::prepareJavaScriptWithSourceMap(
     const std::shared_ptr<const jsi::Buffer> &sourceMapBuf,
     std::string sourceURL) {
   std::pair<std::unique_ptr<hbc::BCProvider>, std::string> bcErr{};
-  auto buffer = std::make_unique<BufferAdapter>(jsiBuffer);
   vm::RuntimeModuleFlags runtimeFlags{};
   runtimeFlags.persistent = true;
 
-  bool isBytecode = isHermesBytecode(buffer->data(), buffer->size());
+  bool isBytecode = isHermesBytecode(jsiBuffer->data(), jsiBuffer->size());
 #ifdef HERMESVM_PLATFORM_LOGGING
   hermesLog(
       "HermesVM", "Prepare JS on %s.", isBytecode ? "bytecode" : "source");
@@ -1444,18 +1475,17 @@ HermesRuntimeImpl::prepareJavaScriptWithSourceMap(
       throw std::logic_error("Source map cannot be specified with bytecode");
     }
     bcErr = hbc::BCProviderFromBuffer::createBCProviderFromBuffer(
-        std::move(buffer));
+        std::make_unique<BufferAdapter>(jsiBuffer));
   } else {
 #if defined(HERMESVM_LEAN)
     bcErr.second = "prepareJavaScript source compilation not supported";
 #else
     std::unique_ptr<::hermes::SourceMap> sourceMap{};
     if (sourceMapBuf) {
+      auto buf0 = ensureZeroTerminated(sourceMapBuf);
       // Convert the buffer into a form the parser needs.
       llvh::MemoryBufferRef mbref(
-          llvh::StringRef(
-              (const char *)sourceMapBuf->data(), sourceMapBuf->size()),
-          "");
+          llvh::StringRef((const char *)buf0->data(), buf0->size()), "");
       ::hermes::SimpleDiagHandler diag;
       ::hermes::SourceErrorManager sm;
       diag.installInto(sm);
@@ -1467,7 +1497,10 @@ HermesRuntimeImpl::prepareJavaScriptWithSourceMap(
       }
     }
     bcErr = hbc::BCProviderFromSrc::createBCProviderFromSrc(
-        std::move(buffer), sourceURL, std::move(sourceMap), compileFlags_);
+        ensureZeroTerminated(jsiBuffer),
+        sourceURL,
+        std::move(sourceMap),
+        compileFlags_);
 #endif
   }
   if (!bcErr.first) {