diff --git a/Makefile b/Makefile
index 91f067ef8..d42558ab8 100644
--- a/Makefile
+++ b/Makefile
@@ -624,7 +624,10 @@ opam.lock: opam
 	  echo "ERROR: This is because opam.lock is generated from the HEAD commit." 1>&2; \
 	  exit 1; \
 	fi
+# allow users to not force a run of opam update since it's very slow
+ifeq ($(NO_OPAM_UPDATE),)
 	$(QUIET)$(call silent_on_success,opam update,$(OPAM) update)
+endif
 	$(QUIET)$(call silent_on_success,installing dependencies $(INFER_PKG_OPAMLOCK) opam package,\
 	  OPAMSWITCH=$(OPAMSWITCH); \
 	  $(OPAM) pin add --yes --no-action -k git $(INFER_PKG_OPAMLOCK) .#HEAD; \
diff --git a/opam.lock b/opam.lock
index ec3ec7a6e..e06990984 100644
--- a/opam.lock
+++ b/opam.lock
@@ -27,7 +27,7 @@ core_kernel = v0.11.1
 cppo = 1.6.4
 cppo_ocamlbuild = 1.6.0
 ctypes = 0.14.0
-dune = 1.1.0
+dune = 1.1.1
 easy-format = 1.3.1
 elina = 1.1
 extlib = 1.7.5