diff --git a/Source/GNUmakefile b/Source/GNUmakefile
index 5feedec5e..82151954f 100644
--- a/Source/GNUmakefile
+++ b/Source/GNUmakefile
@@ -149,6 +149,7 @@ GSFontInfo.m \
 GSTable.m \
 GSHbox.m \
 GSVbox.m \
+GSSimpleLayoutManager.m \
 Parsers/attributedStringConsumer.m \
 Parsers/RTFProducer.m