diff --git a/src/libtomahawk/Album.cpp b/src/libtomahawk/Album.cpp
index 89b46eef5..c2a9bac87 100644
--- a/src/libtomahawk/Album.cpp
+++ b/src/libtomahawk/Album.cpp
@@ -201,9 +201,12 @@ Album::id() const
         m_waitingForId = false;
 
         if ( m_id > 0 )
+        {
+            QMutexLocker lock( &s_mutex );
             s_albumsById[ m_id ] = m_ownRef.toStrongRef();
-        s_idMutex.unlock();
+        }
 
+        s_idMutex.unlock();
     }
 
     return finalId;
diff --git a/src/libtomahawk/Artist.cpp b/src/libtomahawk/Artist.cpp
index 03deda53e..29c279ffe 100644
--- a/src/libtomahawk/Artist.cpp
+++ b/src/libtomahawk/Artist.cpp
@@ -280,7 +280,11 @@ Artist::id() const
         m_waitingForFuture = false;
 
         if ( m_id > 0 )
+        {
+            QMutexLocker lock( &s_mutex );
             s_artistsById[ m_id ] = m_ownRef.toStrongRef();
+        }
+
         s_idMutex.unlock();
     }