diff --git a/__tests__/integration/fixtures/error-no-nav-no-docs/project-a/mkdocs.yml b/__tests__/integration/fixtures/error-no-nav-no-docs/project-a/mkdocs.yml
deleted file mode 100644
index 8dcc285..0000000
--- a/__tests__/integration/fixtures/error-no-nav-no-docs/project-a/mkdocs.yml
+++ /dev/null
@@ -1,7 +0,0 @@
-site_name: 'test'
-site_description: 'This is a subdomain site.'
-
-plugins:
-  - monorepo
-
-docs_dir: docs
diff --git a/__tests__/integration/fixtures/error-no-nav-no-docs/docs/index.md b/__tests__/integration/fixtures/ok-no-nav-no-dir/docs/index.md
similarity index 100%
rename from __tests__/integration/fixtures/error-no-nav-no-docs/docs/index.md
rename to __tests__/integration/fixtures/ok-no-nav-no-dir/docs/index.md
diff --git a/__tests__/integration/fixtures/error-no-nav-no-docs/mkdocs.yml b/__tests__/integration/fixtures/ok-no-nav-no-dir/mkdocs.yml
similarity index 100%
rename from __tests__/integration/fixtures/error-no-nav-no-docs/mkdocs.yml
rename to __tests__/integration/fixtures/ok-no-nav-no-dir/mkdocs.yml
diff --git a/__tests__/integration/fixtures/ok-no-nav-no-dir/project-a/docs/README.md b/__tests__/integration/fixtures/ok-no-nav-no-dir/project-a/docs/README.md
new file mode 100644
index 0000000..4104f83
--- /dev/null
+++ b/__tests__/integration/fixtures/ok-no-nav-no-dir/project-a/docs/README.md
@@ -0,0 +1,3 @@
+# Hello world!
+
+This contains a sentence which only exists in the ok/project-a fixture.
diff --git a/__tests__/integration/fixtures/ok-no-nav-no-dir/project-a/mkdocs.yml b/__tests__/integration/fixtures/ok-no-nav-no-dir/project-a/mkdocs.yml
new file mode 100644
index 0000000..ea06b35
--- /dev/null
+++ b/__tests__/integration/fixtures/ok-no-nav-no-dir/project-a/mkdocs.yml
@@ -0,0 +1,5 @@
+site_name: "test"
+site_description: "This is a subdomain site."
+
+plugins:
+  - monorepo
diff --git a/__tests__/integration/test.bats b/__tests__/integration/test.bats
index 2f6ac6f..0fee968 100644
--- a/__tests__/integration/test.bats
+++ b/__tests__/integration/test.bats
@@ -103,6 +103,13 @@ teardown() {
   [[ "$output" == *"This contains a sentence which only exists in the ok/project-a fixture."* ]]
 }
 
+@test "builds a mkdocs site with no nav and no docs_dir key" {
+  cd ${fixturesDir}/ok-no-nav-no-dir
+  assertSuccessMkdocs build
+  assertFileExists site/test/index.html
+  [[ "$output" == *"This contains a sentence which only exists in the ok/project-a fixture."* ]]
+}
+
 @test "builds a mkdocs site with yaml extension" {
   cd ${fixturesDir}/ok-yaml-not-yml
   assertSuccessMkdocs build
@@ -227,12 +234,6 @@ teardown() {
   [[ "$output" == *"[mkdocs-monorepo] The /"*"/__tests__/integration/fixtures/error-include-path-no-docs-folder/project-a/docs path is not valid. Please update your 'nav' with a valid path."* ]]
 }
 
-@test "fails if !include path docs_dir does not contain any files" {
-  cd ${fixturesDir}/error-no-nav-no-docs
-  assertFailedMkdocs build
-  [[ "$output" == *"[mkdocs-monorepo] The file path /"*"/__tests__/integration/fixtures/error-no-nav-no-docs/project-a/mkdocs.yml does not contain a valid 'nav' key in the YAML file. Please include it to indicate how your documentation should be presented in the navigation, or include a 'docs_dir' to indicate that automatic nav generation should be used."* ]]
-}
-
 @test "fails if absolute links aren't supported" {
   cd ${fixturesDir}/include-path-absolute-url
   assertSuccessMkdocs build
diff --git a/mkdocs_monorepo_plugin/parser.py b/mkdocs_monorepo_plugin/parser.py
index 5f00a8e..4a80d5d 100644
--- a/mkdocs_monorepo_plugin/parser.py
+++ b/mkdocs_monorepo_plugin/parser.py
@@ -185,8 +185,9 @@ class IncludeNavLoader:
 
             # This will check if there is a `docs_dir` property on the `mkdocs.yml` file of
             # the sub folder and scaffold the `nav` property from it
-            if self.navYaml and 'nav' not in self.navYaml and "docs_dir" in self.navYaml:
-                docsDirPath = os.path.join(os.path.dirname(self.absNavPath), self.navYaml["docs_dir"])
+            if self.navYaml and 'nav' not in self.navYaml:
+                docsDir = self.navYaml.get("docs_dir", "docs")
+                docsDirPath = os.path.join(os.path.dirname(self.absNavPath), docsDir)
 
                 def navFromDir(path):
                     directory = {}
@@ -242,8 +243,9 @@ class IncludeNavLoader:
         if self.navYaml and 'nav' not in self.navYaml:
             log.critical(
                 "[mkdocs-monorepo] The file path {} ".format(self.absNavPath) +
-                "does not contain a valid 'nav' key in the YAML file. " +
-                "Please include it to indicate how your documentation should be presented in the navigation, " +
+                "does not contain a valid 'nav' key in the YAML file " +
+                "and the docs folder is not the default one, i.e. `docs`. " +
+                "Please include the `nav` key to indicate how your documentation should be presented in the navigation, " +
                 "or include a 'docs_dir' to indicate that automatic nav generation should be used."
             )
             raise SystemExit(1)