diff --git a/core/definitions.mk b/core/definitions.mk
index 033ab30..5f0bf55 100644
--- a/core/definitions.mk
+++ b/core/definitions.mk
@@ -2138,6 +2138,17 @@
 $(hide) $(call commit-change-for-toc,$@)
 endef
 
+# Runs jarjar on an input file.  Jarjar doesn't exit with a nonzero return code
+# when there is a syntax error in a rules file and doesn't write the output
+# file, so removes the output file before running jarjar and check if it exists
+# after running jarjar.
+define transform-jarjar
+echo $($(PRIVATE_PREFIX)DISPLAY) JarJar: $@
+rm -f $@
+$(JAVA) -jar $(JARJAR) process $(PRIVATE_JARJAR_RULES) $< $@
+[ -e $@ ] || (echo "Missing output file"; exit 1)
+endef
+
 # Moves $1.tmp to $1 if necessary. This is designed to be used with
 # .KATI_RESTAT. For kati, this function doesn't update the timestamp
 # of $1 when $1.tmp is identical to $1 so that ninja won't rebuild