diff --git a/asteroid/test-suites/ug-programs/prgm-003.ast b/asteroid/test-suites/ug-programs/prgm-003.ast
index 8c25a17f..1b6e250a 100644
--- a/asteroid/test-suites/ug-programs/prgm-003.ast
+++ b/asteroid/test-suites/ug-programs/prgm-003.ast
@@ -9,5 +9,5 @@
         with n:*pos_int do            -- use first pattern
             return n * fact (n-1).
         with n:*neg_int do            -- use second pattern
-            throw Error("undefined for "+n).
+            throw Error("undefined for "+ tostring (n)).
         end
diff --git a/asteroid/test-suites/ug-programs/prgm-031.ast b/asteroid/test-suites/ug-programs/prgm-031.ast
index 38ffb259..5eb87ebd 100644
--- a/asteroid/test-suites/ug-programs/prgm-031.ast
+++ b/asteroid/test-suites/ug-programs/prgm-031.ast
@@ -6,7 +6,7 @@
         with n if (n is %integer) and (n > 0) do
             return n * factorial (n-1).
         with n if (n is %integer) and (n < 0) do
-            throw Error("factorial is not defined for "+n).
+            throw Error("factorial is not defined for " + tostring (n)).
     end
 
     io @println ("The factorial of 3 is: " + tostring (factorial 3)).
diff --git a/asteroid/test-suites/ug-programs/prgm-031a.ast b/asteroid/test-suites/ug-programs/prgm-031a.ast
index c65ee0d0..64e1608f 100644
--- a/asteroid/test-suites/ug-programs/prgm-031a.ast
+++ b/asteroid/test-suites/ug-programs/prgm-031a.ast
@@ -6,7 +6,7 @@
         with (n:%integer) if n > 0 do
             n * factorial (n-1).
         with (n:%integer) if n < 0 do
-            throw Error("factorial is not defined for "+n).
+            throw Error("factorial is not defined for " + tostring (n)).
     end
 
     io @println ("The factorial of 3 is: " + tostring (factorial 3)).