diff --git a/build-aux/test-env.in b/build-aux/test-env.in
index c153763a56..1657556b19 100644
--- a/build-aux/test-env.in
+++ b/build-aux/test-env.in
@@ -69,16 +69,16 @@ then
     fi
 
     # The configuration directory, for import/export signing keys.
-    NIX_CONF_DIR="@GUIX_TEST_ROOT@/etc"
-    if [ ! -d "$NIX_CONF_DIR" ]
+    GUIX_CONFIGURATION_DIRECTORY="@GUIX_TEST_ROOT@/etc"
+    if [ ! -d "$GUIX_CONFIGURATION_DIRECTORY" ]
     then
 	# Copy the keys so that the secret key has the right permissions (the
 	# daemon errors out when this is not the case.)
-	mkdir -p "$NIX_CONF_DIR"
+	mkdir -p "$GUIX_CONFIGURATION_DIRECTORY"
 	cp "@abs_top_srcdir@/tests/signing-key.sec"	\
 	    "@abs_top_srcdir@/tests/signing-key.pub"	\
-	    "$NIX_CONF_DIR"
-	chmod 400 "$NIX_CONF_DIR/signing-key.sec"
+	    "$GUIX_CONFIGURATION_DIRECTORY"
+	chmod 400 "$GUIX_CONFIGURATION_DIRECTORY/signing-key.sec"
     fi
 
     # A place to store data of the substituter.
@@ -100,7 +100,7 @@ then
 	NIX_LOCALSTATE_DIR NIX_LOG_DIR NIX_STATE_DIR NIX_DB_DIR	\
 	NIX_ROOT_FINDER GUIX_BINARY_SUBSTITUTE_URL		\
         GUIX_ALLOW_UNAUTHENTICATED_SUBSTITUTES			\
-        NIX_CONF_DIR XDG_CACHE_HOME NIXPKGS
+        GUIX_CONFIGURATION_DIRECTORY XDG_CACHE_HOME NIXPKGS
 
     # Launch the daemon without chroot support because is may be
     # unavailable, for instance if we're not running as root.
diff --git a/gnu/packages/patches/hydra-automake-1.15.patch b/gnu/packages/patches/hydra-automake-1.15.patch
index 0d8fa98519..91c7b9202b 100644
--- a/gnu/packages/patches/hydra-automake-1.15.patch
+++ b/gnu/packages/patches/hydra-automake-1.15.patch
@@ -23,7 +23,7 @@ Automake's parallel test harness.
 -  HYDRA_HOME="$(top_srcdir)/src"			\
 -  HYDRA_CONFIG=						\
 -  NIX_REMOTE=						\
--  NIX_CONF_DIR="$(abs_builddir)/nix/etc/nix"		\
+-  GUIX_CONFIGURATION_DIRECTORY="$(abs_builddir)/nix/etc/nix"		\
 -  NIX_STATE_DIR="$(abs_builddir)/nix/var/nix"		\
 -  NIX_MANIFESTS_DIR="$(abs_builddir)/nix/var/nix/manifests"	\
 -  NIX_STORE_DIR="$(abs_builddir)/nix/store"			\
@@ -39,7 +39,7 @@ Automake's parallel test harness.
 +  HYDRA_HOME="$(top_srcdir)/src"; export HYDRA_HOME;	\
 +  HYDRA_CONFIG=; export HYDRA_CONFIG;			\
 +  NIX_REMOTE=; export NIX_REMOTE;			\
-+  NIX_CONF_DIR="$(abs_builddir)/nix/etc/nix"; export NIX_CONF_DIR; \
++  GUIX_CONFIGURATION_DIRECTORY="$(abs_builddir)/nix/etc/nix"; export GUIX_CONFIGURATION_DIRECTORY; \
 +  NIX_STATE_DIR="$(abs_builddir)/nix/var/nix"; export NIX_STATE_DIR; \
 +  NIX_MANIFESTS_DIR="$(abs_builddir)/nix/var/nix/manifests"; export NIX_MANIFESTS_DIR; \
 +  NIX_STORE_DIR="$(abs_builddir)/nix/store"; export NIX_STORE_DIR; \
diff --git a/guix/config.scm.in b/guix/config.scm.in
index d7df9f7d2b..adffa0cfec 100644
--- a/guix/config.scm.in
+++ b/guix/config.scm.in
@@ -59,8 +59,8 @@
   (or (getenv "NIX_STATE_DIR") "@guix_localstatedir@/guix"))
 
 (define %config-directory
-  ;; This must match `NIX_CONF_DIR' as defined in `nix/local.mk'.
-  (or (getenv "NIX_CONF_DIR") "@guix_sysconfdir@/guix"))
+  ;; This must match `GUIX_CONFIGURATION_DIRECTORY' as defined in `nix/local.mk'.
+  (or (getenv "GUIX_CONFIGURATION_DIRECTORY") "@guix_sysconfdir@/guix"))
 
 (define %guix-register-program
   ;; The 'guix-register' program.
diff --git a/nix/libstore/globals.cc b/nix/libstore/globals.cc
index 84fc885eba..65dad24d91 100644
--- a/nix/libstore/globals.cc
+++ b/nix/libstore/globals.cc
@@ -67,7 +67,7 @@ void Settings::processEnvironment()
     nixLogDir = canonPath(getEnv("NIX_LOG_DIR", NIX_LOG_DIR));
     nixStateDir = canonPath(getEnv("NIX_STATE_DIR", NIX_STATE_DIR));
     nixDBPath = getEnv("NIX_DB_DIR", nixStateDir + "/db");
-    nixConfDir = canonPath(getEnv("NIX_CONF_DIR", NIX_CONF_DIR));
+    nixConfDir = canonPath(getEnv("GUIX_CONFIGURATION_DIRECTORY", GUIX_CONFIGURATION_DIRECTORY));
     nixLibexecDir = canonPath(getEnv("NIX_LIBEXEC_DIR", NIX_LIBEXEC_DIR));
     nixBinDir = canonPath(getEnv("NIX_BIN_DIR", NIX_BIN_DIR));
     nixDaemonSocketFile = canonPath(nixStateDir + DEFAULT_SOCKET_PATH);
diff --git a/nix/local.mk b/nix/local.mk
index 07a92f74ea..b0e9bc1a2b 100644
--- a/nix/local.mk
+++ b/nix/local.mk
@@ -106,7 +106,7 @@ libstore_a_CPPFLAGS =				\
   -DNIX_DATA_DIR=\"$(datadir)\"			\
   -DNIX_STATE_DIR=\"$(localstatedir)/guix\"	\
   -DNIX_LOG_DIR=\"$(localstatedir)/log/guix\"	\
-  -DNIX_CONF_DIR=\"$(sysconfdir)/guix\"		\
+  -DGUIX_CONFIGURATION_DIRECTORY=\"$(sysconfdir)/guix\"		\
   -DNIX_LIBEXEC_DIR=\"$(libexecdir)\"		\
   -DNIX_BIN_DIR=\"$(bindir)\"			\
   -DOPENSSL_PATH="\"guix-authenticate\""	\