diff --git a/tests/asm/meson.build b/tests/asm/meson.build
index 8e9d4f4..4f66c9b 100644
--- a/tests/asm/meson.build
+++ b/tests/asm/meson.build
@@ -49,6 +49,8 @@ asm_tests = {
     'setwd-2': {},
     'setwd-invalidate-regs-1': {},
     'setwd-invalidate-regs-2': {},
+    'setwd-psize-1': {},
+    'setwd-psize-2': { 'should_fail': true },
     'setbn-invalidate-regs-1': {},
     'setbn-invalidate-regs-2': { 'should_fail': true },
     'setbp-invalidate-regs-1': {},
diff --git a/tests/asm/win/setwd-psize-1.S b/tests/asm/win/setwd-psize-1.S
new file mode 100644
index 0000000..212e97a
--- /dev/null
+++ b/tests/asm/win/setwd-psize-1.S
@@ -0,0 +1,20 @@
+#include "test_start.S"
+
+        setwd wsz=8, nfx=1
+
+        disp %ctpr1, 0f
+        // psize = (8 - 4) * 2 = 8 regs
+        call %ctpr1, wbs=4
+
+        disp %ctpr1, 0f
+        // psize = (8 - 8) * 2 = 0 regs
+        call %ctpr1, wbs=8
+
+#include "test_end.S"
+
+0:
+    {
+        setwd wsz=4, nfx=1
+        return %ctpr3
+    }
+        ct %ctpr3
diff --git a/tests/asm/win/setwd-psize-2.S b/tests/asm/win/setwd-psize-2.S
new file mode 100644
index 0000000..a62104e
--- /dev/null
+++ b/tests/asm/win/setwd-psize-2.S
@@ -0,0 +1,21 @@
+#include "test_start.S"
+
+    {
+        setwd wsz=16, nfx=1
+        disp %ctpr1, 0f
+    }
+    {
+        // psize = (16 - 4) * 2 = 24 regs
+        call %ctpr1, wbs=4
+    }
+
+#include "test_end.S"
+
+0:
+    // psize = 24
+    {
+        // try to set wsz lower than psize
+        setwd wsz=4, nfx=1
+        return %ctpr3
+    }
+        ct %ctpr3