diff --git a/.gitignore b/.gitignore
index 4c0191f692..64f72aee5e 100644
--- a/.gitignore
+++ b/.gitignore
@@ -32,3 +32,6 @@ tests/*.out
 # Python cache files
 ######################
 __pycache__/
+
+# Customized Makefile overrides
+GNUmakefile