diff --git a/util/mk1mf.pl b/util/mk1mf.pl
index 90ae84b2f6ec436dc7daa8a7c9844ed5a4007825..3da139dd326d21d7a2c4dc27dad4ee093745099c 100755
--- a/util/mk1mf.pl
+++ b/util/mk1mf.pl
@@ -455,6 +455,11 @@ for (;;)
 	}
 close(IN);
 
+# Remove opensslconf.h so it doesn't get updated if we configure a
+# different branch.
+$exheader =~ s/[^ ]+\/opensslconf.h//;
+$header =~ s/[^ ]+\/opensslconf.h//;
+
 if ($fips)
 	{
 
@@ -756,6 +761,7 @@ $banner
 # This needs to be invoked once, when the makefile is first constructed, or
 # after cleaning.
 init: \$(TMP_D) \$(LIB_D) \$(INC_D) \$(INCO_D) \$(BIN_D) \$(TEST_D) headers
+	\$(PERL) \$(SRC_D)/util/copy-if-different.pl "\$(SRC_D)/crypto/opensslconf.h" "\$(INCO_D)/opensslconf.h"
 
 headers: \$(HEADER) \$(EXHEADER)