diff --git a/INSTALL.md b/INSTALL.md
index 7a545e8f0..5987ca5d5 100644
--- a/INSTALL.md
+++ b/INSTALL.md
@@ -14,7 +14,7 @@ this command accepts the following variables:
  * **SBINDIR**, to specify where to put CRIU executable (`$(PREFIX)/sbin` by default);
  * **MANDIR**, to specify directory for manual pages (`$(PREFIX)/share/man` by default);
  * **SYSTEMDUNITDIR**, to specify place where systemd units are living (`$(PREFIX)/lib/systemd/system` by default);
- * **LIBDIR**, to specify directory where to put libraries (`$(PREFIX)/lib` by default).
+ * **LIBDIR**, to specify directory where to put libraries (guess the correct path  by default).
 
 Thus one can type
 
diff --git a/Makefile.install b/Makefile.install
index b3337e640..923151389 100644
--- a/Makefile.install
+++ b/Makefile.install
@@ -1,25 +1,25 @@
 #
 # Installation paths.
-PREFIX		?= /usr/local
-BINDIR		?= $(PREFIX)/bin
-SBINDIR		?= $(PREFIX)/sbin
-MANDIR		?= $(PREFIX)/share/man
-SYSTEMDUNITDIR	?= $(PREFIX)/lib/systemd/system
-LOGROTATEDIR	?= $(PREFIX)/etc/logrotate.d
-LIBDIR		?= $(PREFIX)/lib
-INCLUDEDIR	?= $(PREFIX)/include
-LIBEXECDIR	?= $(PREFIX)/libexec
+PREFIX		:= /usr/local
+BINDIR		:= $(PREFIX)/bin
+SBINDIR		:= $(PREFIX)/sbin
+MANDIR		:= $(PREFIX)/share/man
+SYSTEMDUNITDIR	:= $(PREFIX)/lib/systemd/system
+LOGROTATEDIR	:= $(PREFIX)/etc/logrotate.d
+LIBDIR		:= $(PREFIX)/lib
+INCLUDEDIR	:= $(PREFIX)/include
+LIBEXECDIR	:= $(PREFIX)/libexec
 
 #
 # For recent Debian/Ubuntu with multiarch support.
-DEB_HOST_MULTIARCH ?= $(shell dpkg-architecture -qDEB_HOST_MULTIARCH 2>/dev/null)
+DEB_HOST_MULTIARCH := $(shell dpkg-architecture -qDEB_HOST_MULTIARCH 2>/dev/null)
 ifneq "$(DEB_HOST_MULTIARCH)" ""
-        LIBDIR			?= $(PREFIX)/lib/$(DEB_HOST_MULTIARCH)
+        LIBDIR			:= $(PREFIX)/lib/$(DEB_HOST_MULTIARCH)
 else
         #
         # For most other systems
         ifeq "$(shell uname -m)" "x86_64"
-                LIBDIR		?= $(PREFIX)/lib64
+                LIBDIR		:= $(PREFIX)/lib64
         endif
 endif