diff --git a/stackinator/builder.py b/stackinator/builder.py
index 2c05e3c..c3de44d 100644
--- a/stackinator/builder.py
+++ b/stackinator/builder.py
@@ -232,6 +232,8 @@ def generate(self, recipe):
                     pre_install_hook=recipe.pre_install_hook,
                     spack_version=spack_version,
                     spack_meta=spack_meta,
+                    # pass source_mirrors to Makefile render
+                    source_mirrors=recipe.config.get("source_mirrors", {}),
                     exclude_from_cache=["nvhpc", "cuda", "perl"],
                     verbose=False,
                 )
diff --git a/stackinator/schema/config.json b/stackinator/schema/config.json
index d6fec3a..4b91011 100644
--- a/stackinator/schema/config.json
+++ b/stackinator/schema/config.json
@@ -64,6 +64,13 @@
                 }
             }
         },
+        "source_mirrors" : {
+            "type" : "object",
+            "additionalProperties": {
+                "type" : "string"
+            },
+            "default": {}
+        },
         "modules" : {
             "type": "boolean"
         },
diff --git a/stackinator/templates/Makefile b/stackinator/templates/Makefile
index 10a0ea5..ca8fb31 100644
--- a/stackinator/templates/Makefile
+++ b/stackinator/templates/Makefile
@@ -32,13 +32,21 @@ pre-install: spack-setup
 	$(SANDBOX) $(STORE)/pre-install-hook
 
 mirror-setup: spack-setup{% if pre_install_hook %} pre-install{% endif %}
-
+	
 	{% if cache %}
 	$(SANDBOX) $(SPACK) buildcache keys --install --trust
 	{% if cache.key %}
 	$(SANDBOX) $(SPACK) gpg trust {{ cache.key }}
 	{% endif %}
 	{% endif %}
+	{% if source_mirrors %}
+	@echo "Adding mirrors"
+	{% for name, url in source_mirrors.items() | reverse %}
+	$(SANDBOX) $(SPACK) mirror add --scope=site {{ name }} {{ url }}
+	{% endfor %}
+	@echo "Current mirror list:"
+	$(SANDBOX) $(SPACK) mirror list
+	{% endif %}
 	touch mirror-setup
 
 compilers: mirror-setup