diff --git a/src/libtomahawk/Album.cpp b/src/libtomahawk/Album.cpp
index 07487230e..cd7661897 100644
--- a/src/libtomahawk/Album.cpp
+++ b/src/libtomahawk/Album.cpp
@@ -214,7 +214,10 @@ Album::id() const
         m_waitingForId = false;
 
         if ( m_id > 0 )
+        {
+            QMutexLocker lock( &s_mutex );
             s_albumsById[ m_id ] = m_ownRef.toStrongRef();
+        }
 
         s_idMutex.unlock();
     }
diff --git a/src/libtomahawk/Artist.cpp b/src/libtomahawk/Artist.cpp
index 88b45ab2b..d8cd6393f 100644
--- a/src/libtomahawk/Artist.cpp
+++ b/src/libtomahawk/Artist.cpp
@@ -306,7 +306,10 @@ Artist::id() const
         m_waitingForFuture = false;
 
         if ( m_id > 0 )
+        {
+            QMutexLocker lock( &s_mutex );
             s_artistsById[ m_id ] = m_ownRef.toStrongRef();
+        }
 
         s_idMutex.unlock();
     }