diff --git a/Makefile b/Makefile
index 5d8f3216..ae8bff13 100644
--- a/Makefile
+++ b/Makefile
@@ -4,7 +4,9 @@ CFLAGS=-O2
 
 # Additional programs that are used during the compilation process.
 EMACS ?= emacs
-GZIP ?= gzip
+# Lowercase to avoid clash with GZIP environment variable for passing
+# arguments to gzip.
+gzip = gzip
 
 # Additional flags that we will append to whatever the user set.
 # These aren't intended for the user to manipulate.
diff --git a/Makefile.local b/Makefile.local
index 5fd5d4f4..b6d3db3c 100644
--- a/Makefile.local
+++ b/Makefile.local
@@ -23,7 +23,7 @@ notmuch: $(notmuch_client_modules) lib/notmuch.a
 	$(call quiet,CXX) $^ $(LDFLAGS) -o $@
 
 notmuch.1.gz: notmuch.1
-	$(call quiet,GZIP) --stdout $^ > $@
+	$(call quiet,gzip) --stdout $^ > $@
 
 install: all notmuch.1.gz
 	for d in $(DESTDIR)$(prefix)/bin/ $(DESTDIR)$(prefix)/share/man/man1 \