diff --git a/Makefile b/Makefile
index 3701d351..d37c8cef 100644
--- a/Makefile
+++ b/Makefile
@@ -1,3 +1,4 @@
+.SHELLFLAGS = -ec
 PACKAGES ?= mountinfo mount
 BINDIR ?= _build/bin
 
diff --git a/mountinfo/mountinfo_linux.go b/mountinfo/mountinfo_linux.go
index 20630248..cdfd37da 100644
--- a/mountinfo/mountinfo_linux.go
+++ b/mountinfo/mountinfo_linux.go
@@ -193,10 +193,10 @@ func unescape(path string) (string, error) {
 		case '0', '1', '2', '3', '4', '5', '6', '7':
 			v := c - '0'
 			for j := 2; j < 4; j++ { // one digit already; two more
-				x := s[j] - '0'
-				if x < 0 || x > 7 {
+				if s[j] < '0' || s[j] > '7' {
 					return "", fmt.Errorf("bad escape sequence %q: not a digit", s[:3])
 				}
+				x := s[j] - '0'
 				v = (v << 3) | x
 			}
 			if v > 255 {
diff --git a/mountinfo/mountinfo_linux_test.go b/mountinfo/mountinfo_linux_test.go
index 7c060e2f..868bad90 100644
--- a/mountinfo/mountinfo_linux_test.go
+++ b/mountinfo/mountinfo_linux_test.go
@@ -509,7 +509,7 @@ func TestParseMountinfoWithSpaces(t *testing.T) {
 			Opts:       "rw,relatime",
 			Optional:   "",
 			Fstype:     "cifs",
-			Source:     `//foo/BLA\040BLA\040BLA/`,
+			Source:     `//foo/BLA BLA BLA/`,
 			VfsOpts:    `rw,sec=ntlm,cache=loose,unc=\\foo\BLA`,
 		},
 		{