diff --git a/functions.mk b/functions.mk
index 1287e4321e..c92cdbc54e 100644
--- a/functions.mk
+++ b/functions.mk
@@ -9,3 +9,6 @@ filename-to-dep = $(dir $1).$(notdir $1).dep
 # Return the full path to a program by looking it up in $PATH, or the
 # empty string if not found.
 find-program = $(shell for i in $$(IFS=: ; echo $$PATH); do p=$$i/$(strip $1); if [ -e $$p ]; then echo $$p; break; fi; done)
+
+# Remove trailing slash.
+remove-trailing-slash = $(patsubst %/,%,$(1))
diff --git a/install.mk b/install.mk
index e4bc734e11..0fe4cf938d 100644
--- a/install.mk
+++ b/install.mk
@@ -1,7 +1,7 @@
 # Add a rule for creating $(1) as a directory.  This template may be
 # called multiple times for the same directory.
 define create-dir
-   _i := $(DESTDIR)$$(strip $(1))
+   _i := $$(call remove-trailing-slash, $(DESTDIR)$$(strip $(1)))
   ifndef $$(_i)_SEEN
     $$(_i)_SEEN = 1
     $$(_i):