diff --git a/kg/main.go b/kg/main.go
index 22ad26e..c5b8397 100644
--- a/kg/main.go
+++ b/kg/main.go
@@ -91,6 +91,7 @@ func main() {
 		inputFilenames := flag.Args()[1:]
 		for _, inputFilename := range inputFilenames {
 			inputFile, err := os.Open(inputFilename)
+			defer inputFile.Close()
 			if err != nil {
 				fmt.Printf("%s: %s: No such file or directory\n", os.Args[0], inputFilename)
 			} else {
@@ -102,8 +103,14 @@ func main() {
 					if fileStat.Mode().IsDir() {
 						fmt.Printf("%s: %s: Is a directory\n", os.Args[0], inputFilename)
 					} else {
-						if fileContainsNullChar(inputFile) {
-							fmt.Printf("%s: %s: Is a binary file\n", os.Args[0], inputFilename)
+						var nullCharPresent bool
+						if nullCharPresent, err = fileContainsNullChar(inputFilename); nullCharPresent {
+							if err != nil {
+								fmt.Printf("%v\n", err)
+								os.Exit(1)
+							} else {
+								fmt.Printf("%s: %s: Is a binary file\n", os.Args[0], inputFilename)
+							}
 						} else {
 							inputFiles = append(inputFiles, inputFile)
 						}