diff --git a/cmd/s3backup/main_test.go b/cmd/s3backup/main_test.go
index e88c569..8fd3e79 100644
--- a/cmd/s3backup/main_test.go
+++ b/cmd/s3backup/main_test.go
@@ -7,9 +7,18 @@ import (
 )
 
 func TestCheckPaths(t *testing.T) {
+	localPath = "s3://foo/bar.txt"
+	remotePath = "s3://foo/bar.txt"
+	assert.Error(t, checkPaths(), "cannot have two remote paths")
+
+	localPath = "bar.txt"
+	remotePath = "bar.txt"
+	assert.Error(t, checkPaths(), "cannot have two local paths")
+
 	localPath = "bar.txt"
 	remotePath = "s3://foo/bar.txt"
 	assert.NilError(t, checkPaths())
+
 	localPath = "s3://foo/bar.txt"
 	remotePath = "bar.txt"
 	assert.NilError(t, checkPaths())