diff --git a/add.nim b/add.nim
index 7d01b92..5d5b108 100644
--- a/add.nim
+++ b/add.nim
@@ -2,6 +2,7 @@ import cligen, sequtils
 import common
 
 proc main(integers:seq[int]) =
-    echo integers.foldl(a + b)
+    if integers.len > 0:
+        echo integers.foldl(a + b)
 
 dispatch(main, version=("version", nimbaseVersion))
diff --git a/mul.nim b/mul.nim
index c931f86..c7f1246 100644
--- a/mul.nim
+++ b/mul.nim
@@ -2,6 +2,7 @@ import cligen, sequtils
 import common
 
 proc main(integers:seq[int]) =
-    echo integers.foldl(a * b)
+    if integers > 0:
+        echo integers.foldl(a * b)
 
 dispatch(main, version=("version", nimbaseVersion))
diff --git a/sub.nim b/sub.nim
index ba34c8e..6f4a29d 100644
--- a/sub.nim
+++ b/sub.nim
@@ -2,6 +2,7 @@ import cligen, sequtils
 import common
 
 proc main(integers:seq[int]) =
-    echo integers.foldl(a - b)
+    if integers > 0:
+        echo integers.foldl(a - b)
 
 dispatch(main, version=("version", nimbaseVersion))