diff --git a/Makefile.in b/Makefile.in
index e8443ca1ef0..64da5f26836 100644
--- a/Makefile.in
+++ b/Makefile.in
@@ -57,6 +57,9 @@ endif
 
 export PATH AWK SED
 
+# "make report" depends on the default installation of riscv-sim.exp.
+unexport DEJAGNU
+
 MULTILIB_FLAGS := @multilib_flags@
 MULTILIB_GEN := @multilib_gen@
 ifeq ($(MULTILIB_GEN),)