diff --git a/src/external/rawspeed/RawSpeed/RawImage.cpp b/src/external/rawspeed/RawSpeed/RawImage.cpp
index 4c63e57cb381..31867c2600e9 100644
--- a/src/external/rawspeed/RawSpeed/RawImage.cpp
+++ b/src/external/rawspeed/RawSpeed/RawImage.cpp
@@ -394,11 +394,18 @@ RawImage& RawImage::operator=(const RawImage & p) {
   if (this == &p)      // Same object?
     return *this;      // Yes, so skip assignment, and just return *this.
   pthread_mutex_lock(&p_->mymutex);
+  // Retain the old RawImageData before overwriting it
   RawImageData* const old = p_;
   p_ = p.p_;
+  // Increment use on new data
   ++p_->dataRefCount;
-  if (--old->dataRefCount == 0) delete old;
-  pthread_mutex_unlock(&p_->mymutex);
+  // If the RawImageData previously used by "this" is unused, delete it.
+  if (--old->dataRefCount == 0) {
+      pthread_mutex_unlock(&(old->mymutex));
+      delete old;
+  } else {
+      pthread_mutex_unlock(&(old->mymutex));
+  }
   return *this;
 }