diff --git a/apt_query.go b/apt_query.go
index 8975b76..665933c 100644
--- a/apt_query.go
+++ b/apt_query.go
@@ -65,7 +65,7 @@ func getPackages(names []string) AptPackages {
 				pkg.Name = strings.TrimSpace(strings.Split(line, ":")[1])
 			} else if strings.HasPrefix(line, "Version: ") {
 				pkg.Version = strings.TrimSpace(strings.Split(line, ":")[1])
-			} else if strings.HasPrefix(line, "N: ") || strings.HasPrefix(line, "E: ") {
+			} else if strings.HasPrefix(line, "N: Unable to locate package ") || strings.HasPrefix(line, "E: ") {
 				if !contains(errorMessages, line) {
 					errorMessages = append(errorMessages, line)
 				}
diff --git a/apt_query_test.go b/apt_query_test.go
index 65beae0..ea585d3 100644
--- a/apt_query_test.go
+++ b/apt_query_test.go
@@ -28,6 +28,9 @@ func (r *RunResult) expectSuccessfulOut(expected string) {
 		r.TestContext.Errorf("Error running command: %v", r.Err)
 		return
 	}
+	if r.Stderr != "" {
+		r.TestContext.Errorf("Unexpected stderr messages found.\nExpected: none\nActual:\n'%s'", r.Stderr)
+	}
 	if r.Stdout != expected+"\n" { // Output will always have a end of output newline.
 		r.TestContext.Errorf("Unexpected stdout found.\nExpected:\n'%s'\nActual:\n'%s'", expected, r.Stdout)
 	}