diff --git a/subjects/raid1a.en.md b/subjects/raid1a.en.md
index aa683d8a..0e02c912 100644
--- a/subjects/raid1a.en.md
+++ b/subjects/raid1a.en.md
@@ -6,7 +6,7 @@ Write a function `Raid1a` that prints a **valid** rectangle of width `x` and of
 
 The function must draw the rectangles as in the examples.
 
-`x` and `y` will always be positive numbers.
+`x` and `y` will always be positive numbers. Otherwise, the function should print nothing.
 
 ### Expected function
 
diff --git a/subjects/raid1b.en.md b/subjects/raid1b.en.md
index cc90bf52..41b70568 100644
--- a/subjects/raid1b.en.md
+++ b/subjects/raid1b.en.md
@@ -6,7 +6,7 @@ Write a function `Raid1b` that prints a **valid** rectangle of width `x` and of
 
 The function must draw the rectangles as in the examples.
 
-`x` and `y` will always be positive numbers.
+`x` and `y` will always be positive numbers. Otherwise, the function should print nothing.
 
 ### Expected function
 
diff --git a/subjects/raid1c.en.md b/subjects/raid1c.en.md
index 82bef432..77aa21ee 100644
--- a/subjects/raid1c.en.md
+++ b/subjects/raid1c.en.md
@@ -6,7 +6,7 @@ Write a function `Raid1c` that prints a **valid** rectangle of width `x` and of
 
 The function must draw the rectangles as in the examples.
 
-`x` and `y` will always be positive numbers.
+`x` and `y` will always be positive numbers. Otherwise, the function should print nothing.
 
 ### Expected function
 
diff --git a/subjects/raid1d.en.md b/subjects/raid1d.en.md
index 32f8495a..3bfd67d4 100644
--- a/subjects/raid1d.en.md
+++ b/subjects/raid1d.en.md
@@ -6,7 +6,7 @@ Write a function `Raid1d` that prints a **valid** rectangle of width `x` and of
 
 The function must draw the rectangles as in the examples.
 
-`x` and `y` will always be positive numbers.
+`x` and `y` will always be positive numbers. Otherwise, the function should print nothing.
 
 ### Expected function
 
diff --git a/subjects/raid1e.en.md b/subjects/raid1e.en.md
index 3762f271..36d54a6e 100644
--- a/subjects/raid1e.en.md
+++ b/subjects/raid1e.en.md
@@ -6,7 +6,7 @@ Write a function `Raid1e` that prints a **valid** rectangle of width `x` and of
 
 The function must draw the rectangles as in the examples.
 
-`x` and `y` will always be positive numbers.
+`x` and `y` will always be positive numbers. Otherwise, the function should print nothing.
 
 ### Expected function