diff --git a/Makefile b/Makefile
index 9f9c3b5..b816089 100644
--- a/Makefile
+++ b/Makefile
@@ -607,6 +607,13 @@
 include/config/auto.conf: ;
 endif # $(dot-config)
 
+# For the kernel to actually contain only the needed exported symbols,
+# we have to build modules as well to determine what those symbols are.
+# (this can be evaluated only once include/config/auto.conf has been included)
+ifdef CONFIG_TRIM_UNUSED_KSYMS
+  KBUILD_MODULES := 1
+endif
+
 # The all: target is the default when no target is given on the
 # command line.
 # This allow a user to issue only 'make' to build a kernel including modules
@@ -944,7 +951,7 @@
 endif
 ifdef CONFIG_TRIM_UNUSED_KSYMS
 	$(Q)$(CONFIG_SHELL) $(srctree)/scripts/adjust_autoksyms.sh \
-	  "$(MAKE) KBUILD_MODULES=1 -f $(srctree)/Makefile vmlinux_prereq"
+	  "$(MAKE) -f $(srctree)/Makefile vmlinux"
 endif
 
 # standalone target for easier testing