diff --git a/tests/css/parser/Makefile.am b/tests/css/parser/Makefile.am
index 84a24225d5..9ffd43790c 100644
--- a/tests/css/parser/Makefile.am
+++ b/tests/css/parser/Makefile.am
@@ -68,6 +68,9 @@ EXTRA_DIST += \
 	integer.ref.css \
 	no-semicolon.css \
 	no-semicolon.ref.css \
+	pseudo-classes-unknown.css \
+	pseudo-classes-unknown.errors \
+	pseudo-classes-unknown.ref.css \
 	selector.css \
 	selector.ref.css \
 	simple.css
diff --git a/tests/css/parser/pseudo-classes-unknown.css b/tests/css/parser/pseudo-classes-unknown.css
new file mode 100644
index 0000000000..fa82e7da46
--- /dev/null
+++ b/tests/css/parser/pseudo-classes-unknown.css
@@ -0,0 +1,23 @@
+:nobody-knows-me {
+  int-property: 42;
+}
+
+:nobody-knows-me(really) {
+  int-property: 42;
+}
+
+:a:lot:of:unkwnown:pseudo:classes(some):of(them):with:functions( spaces ) {
+  int-property: 42;
+}
+
+:nth-child {
+  int-property: 42;
+}
+
+:nth-child() {
+  int-property: 42;
+}
+
+x, :unknown-pseudo-classes-invalidate-selectors, y {
+  int-property: 42;
+}
diff --git a/tests/css/parser/pseudo-classes-unknown.errors b/tests/css/parser/pseudo-classes-unknown.errors
new file mode 100644
index 0000000000..18b98855e9
--- /dev/null
+++ b/tests/css/parser/pseudo-classes-unknown.errors
@@ -0,0 +1,6 @@
+pseudo-classes-unknown.css:1: error: GTK_CSS_PROVIDER_ERROR_UNKNOWN_VALUE
+pseudo-classes-unknown.css:5: error: GTK_CSS_PROVIDER_ERROR_UNKNOWN_VALUE
+pseudo-classes-unknown.css:9: error: GTK_CSS_PROVIDER_ERROR_UNKNOWN_VALUE
+pseudo-classes-unknown.css:13: error: GTK_CSS_PROVIDER_ERROR_UNKNOWN_VALUE
+pseudo-classes-unknown.css:17: error: GTK_CSS_PROVIDER_ERROR_UNKNOWN_VALUE
+pseudo-classes-unknown.css:21: error: GTK_CSS_PROVIDER_ERROR_UNKNOWN_VALUE
diff --git a/tests/css/parser/pseudo-classes-unknown.ref.css b/tests/css/parser/pseudo-classes-unknown.ref.css
new file mode 100644
index 0000000000..e69de29bb2