diff --git a/Makefile b/Makefile
index 4f13f27..45ecf77 100644
--- a/Makefile
+++ b/Makefile
@@ -1,6 +1,7 @@
 JSONNET_FMT := jsonnet fmt -n 2 --max-blank-lines 2 --string-style s --comment-style s
 
-JB_BINARY:=$(GOPATH)/bin/jb
+JSONNET_BIN := $(GOPATH)/bin/jsonnet
+JB_BINARY := $(GOPATH)/bin/jb
 
 .PHONY: generate vendor fmt manifests
 
@@ -8,7 +9,7 @@ all: manifests
 
 manifests: jsonnet
 	rm -rf manifests
-	./scripts/build.sh main.jsonnet
+	./scripts/build.sh main.jsonnet $(JSONNET_BIN)
 
 update:
 	jb update
diff --git a/manifests/alertmanager-secret.yaml b/manifests/alertmanager-secret.yaml
index 79fc7a2..9be86af 100644
--- a/manifests/alertmanager-secret.yaml
+++ b/manifests/alertmanager-secret.yaml
@@ -1,6 +1,6 @@
 apiVersion: v1
 data:
-  alertmanager.yaml: Imdsb2JhbCI6IAogICJyZXNvbHZlX3RpbWVvdXQiOiAiNW0iCiJyZWNlaXZlcnMiOiAKLSAibmFtZSI6ICJudWxsIgoicm91dGUiOiAKICAiZ3JvdXBfYnkiOiAKICAtICJqb2IiCiAgImdyb3VwX2ludGVydmFsIjogIjVtIgogICJncm91cF93YWl0IjogIjMwcyIKICAicmVjZWl2ZXIiOiAibnVsbCIKICAicmVwZWF0X2ludGVydmFsIjogIjEyaCIKICAicm91dGVzIjogCiAgLSAibWF0Y2giOiAKICAgICAgImFsZXJ0bmFtZSI6ICJEZWFkTWFuc1N3aXRjaCIKICAgICJyZWNlaXZlciI6ICJudWxsIg==
+  alertmanager.yaml: Imdsb2JhbCI6CiAgInJlc29sdmVfdGltZW91dCI6ICI1bSIKInJlY2VpdmVycyI6Ci0gIm5hbWUiOiAibnVsbCIKInJvdXRlIjoKICAiZ3JvdXBfYnkiOgogIC0gImpvYiIKICAiZ3JvdXBfaW50ZXJ2YWwiOiAiNW0iCiAgImdyb3VwX3dhaXQiOiAiMzBzIgogICJyZWNlaXZlciI6ICJudWxsIgogICJyZXBlYXRfaW50ZXJ2YWwiOiAiMTJoIgogICJyb3V0ZXMiOgogIC0gIm1hdGNoIjoKICAgICAgImFsZXJ0bmFtZSI6ICJEZWFkTWFuc1N3aXRjaCIKICAgICJyZWNlaXZlciI6ICJudWxsIg==
 kind: Secret
 metadata:
   name: alertmanager-main
diff --git a/scripts/build.sh b/scripts/build.sh
index f68cd44..708323b 100755
--- a/scripts/build.sh
+++ b/scripts/build.sh
@@ -1,5 +1,13 @@
 #!/usr/bin/env bash
 
+if ! [ -x "$(command -v $2)" ]; then
+    JSONNET_BIN=jsonnet
+    echo "using jsonnet from path"
+else
+    JSONNET_BIN=$2
+    echo "using jsonnet from arg"
+fi
+
 # This script uses arg $1 (name of *.jsonnet file to use) to generate the manifests/*.yaml files.
 
 set -e
@@ -11,6 +19,6 @@ set -o pipefail
 rm -rf manifests
 mkdir manifests
 
-                                               # optional, but we would like to generate yaml, not json
-jsonnet -J vendor -m manifests "${1-example.jsonnet}" | xargs -I{} sh -c 'cat {} | gojsontoyaml > {}.yaml; rm -f {}' -- {}
+# optional, but we would like to generate yaml, not json
+$JSONNET_BIN -J vendor -m manifests "${1-example.jsonnet}" | xargs -I{} sh -c 'cat {} | gojsontoyaml > {}.yaml; rm -f {}' -- {}