diff --git a/makefile b/makefile
index 11846be..183658f 100644
--- a/makefile
+++ b/makefile
@@ -7,7 +7,7 @@ all: epub mobi
 
 retrieve:
 	mkdir -p $(out)
-	cd $(out); for i in $(source); do curl -L -O $$i.md; done
+	cd $(out); for i in $(source); do curl -L -O $$i; done
 
 postprocess:
 	sed -i \
diff --git a/source-urls.txt b/source-urls.txt
index 51d3847..0ffb345 100755
--- a/source-urls.txt
+++ b/source-urls.txt
@@ -1,5 +1,5 @@
-https://www.petekeen.net/keeping-finances-with-ledger
-https://www.petekeen.net/program-your-finances-reporting-for-fun-and-profit
-https://www.petekeen.net/program-your-finances-vacation-tracking
-https://www.petekeen.net/program-your-finances-automated-transactions
-https://www.petekeen.net/a-robust-reporting-system-for-ledger
+https://www.petekeen.net/keeping-finances-with-ledger.md
+https://www.petekeen.net/program-your-finances-reporting-for-fun-and-profit.md
+https://www.petekeen.net/program-your-finances-vacation-tracking.md
+https://www.petekeen.net/program-your-finances-automated-transactions.md
+https://www.petekeen.net/a-robust-reporting-system-for-ledger.md