diff --git a/test/ipa/libipa/meson.build b/test/ipa/libipa/meson.build
index b2cc4b74..c553366a 100644
--- a/test/ipa/libipa/meson.build
+++ b/test/ipa/libipa/meson.build
@@ -4,7 +4,7 @@ libipa_test = [
     {'name': 'fixedpoint', 'sources': ['fixedpoint.cpp']},
     {'name': 'histogram', 'sources': ['histogram.cpp']},
     {'name': 'interpolator', 'sources': ['interpolator.cpp']},
-    {'name': 'pwl', 'sources': ['pwl.cpp']},
+    {'name': 'pwl', 'sources': ['pwl.cpp'], 'should_fail': true },
 ]
 
 foreach test : libipa_test
diff --git a/test/ipa/libipa/pwl.cpp b/test/ipa/libipa/pwl.cpp
index d41a290a..6640b1ab 100644
--- a/test/ipa/libipa/pwl.cpp
+++ b/test/ipa/libipa/pwl.cpp
@@ -43,6 +43,13 @@ protected:
 
 		ASSERT_EQ(pwl.size(), 2);
 
+		/* Test degenerate PWL. */
+		pwl.clear();
+		pwl.append(1, 1);
+		ASSERT_EQ(pwl.eval(0), 1);
+		ASSERT_EQ(pwl.eval(1), 1);
+		ASSERT_EQ(pwl.eval(2), 1);
+
 		return TestPass;
 	}
 };