diff --git a/common/ImageBuffer.cpp b/common/ImageBuffer.cpp
index c88a9795..06c29a00 100644
--- a/common/ImageBuffer.cpp
+++ b/common/ImageBuffer.cpp
@@ -15,15 +15,18 @@ ImageBuffer::ImageBuffer(size_t buffer_size_bytes)
         : buffer_size(buffer_size_bytes) {
 
 #ifdef JFJOCH_USE_NUMA
-    buffer = (uint8_t *) numa_alloc_interleaved(buffer_size);
-#else
-    buffer = (uint8_t *) mmap (nullptr, buffer_size, PROT_READ | PROT_WRITE,
-                               MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) ;
-#endif
+    buffer = static_cast<uint8_t *>(numa_alloc_interleaved(buffer_size));
     if (buffer == nullptr)
         throw JFJochException(JFJochExceptionCategory::MemAllocFailed,
             "Failed to allocate image buffer");
 
+    #else
+    buffer = (uint8_t *) mmap (nullptr, buffer_size, PROT_READ | PROT_WRITE,
+                               MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) ;
+    if (buffer == MAP_FAILED)
+        throw JFJochException(JFJochExceptionCategory::MemAllocFailed,
+                              "Failed to allocate image buffer");
+#endif
     memset(buffer, 0, buffer_size);
 }
 
@@ -241,6 +244,7 @@ void ImageBuffer::GetStartMessage(std::vector<uint8_t> &out_v) {
 }
 
 void ImageBuffer::SaveStartMessage(const std::vector<uint8_t> &msg) {
+    std::unique_lock ul(start_message_mutex);
     start_message = msg;
 }