diff --git a/include/book.h b/include/book.h
index 0f21bc481..04d71b1a3 100644
--- a/include/book.h
+++ b/include/book.h
@@ -48,6 +48,8 @@ class Book
   {
     friend class Book;
    public:
+    uint16_t width = 48;
+    uint16_t height = 48;
     std::string mimeType;
     std::string url;
 
diff --git a/src/book.cpp b/src/book.cpp
index faee20dfe..50a144bb6 100644
--- a/src/book.cpp
+++ b/src/book.cpp
@@ -226,8 +226,12 @@ void Book::setPath(const std::string& path)
 
 const Book::Illustration& Book::getDefaultIllustration() const
 {
-  assert(m_illustrations.size() == 1);
-  return *m_illustrations.front();
+  for ( const auto& ilPtr : m_illustrations ) {
+    if (ilPtr->width == 48 && ilPtr->height == 48) {
+      return *ilPtr;
+    }
+  }
+  throw std::runtime_error("No default illustration");
 }
 
 Book::Illustration& Book::getMutableDefaultIllustration()