diff --git a/Makefile.am b/Makefile.am
index f1896c0..938dffa 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -1,9 +1,9 @@
 AUTOMAKE_OPTIONS = foreign
 SUBDIRS = src man
-nwipe_SOURCES = src/*.c src/*.h
+NWIPESOURCES = src/*.c src/*.h
 
 format:
-	clang-format -i -style=file $(nwipe_SOURCES)
+	clang-format -i -style=file $(NWIPESOURCES)
 
 check-format:
-	clang-format -i -style=file $(nwipe_SOURCES) && git diff-index --quiet HEAD
+	clang-format -i -style=file $(NWIPESOURCES) && git diff-index --quiet HEAD