diff --git a/tests/ui/frontmatter/space-in-infostring.rs b/tests/ui/frontmatter/space-in-infostring.rs
new file mode 100644
index 0000000000000..a8448af113443
--- /dev/null
+++ b/tests/ui/frontmatter/space-in-infostring.rs
@@ -0,0 +1,9 @@
+--- cargo clippy
+//~^ ERROR: invalid infostring for frontmatter
+---
+
+// infostrings cannot have spaces
+
+#![feature(frontmatter)]
+
+fn main() {}
diff --git a/tests/ui/frontmatter/space-in-infostring.stderr b/tests/ui/frontmatter/space-in-infostring.stderr
new file mode 100644
index 0000000000000..b876ddae782e9
--- /dev/null
+++ b/tests/ui/frontmatter/space-in-infostring.stderr
@@ -0,0 +1,10 @@
+error: invalid infostring for frontmatter
+  --> $DIR/space-in-infostring.rs:1:4
+   |
+LL | --- cargo clippy
+   |    ^^^^^^^^^^^^^
+   |
+   = note: frontmatter infostrings must be a single identifier immediately following the opening
+
+error: aborting due to 1 previous error
+