diff --git a/checksum.go b/checksum.go
index 76fa43087..62a910f71 100644
--- a/checksum.go
+++ b/checksum.go
@@ -49,8 +49,9 @@ func checksumHashAndValue(u *url.URL) (checksumHash hash.Hash, checksumValue []b
 		return nil, nil, fmt.Errorf(
 			"unsupported checksum type: %s", checksumType)
 	}
+	file := v[idx+1:]
 
-	checkSums, err := checksumsFromFile(v[idx+1:], u)
+	checkSums, err := checksumsFromFile(file, u)
 	if err != nil {
 		return nil, nil, err
 	}
@@ -60,11 +61,12 @@ func checksumHashAndValue(u *url.URL) (checksumHash hash.Hash, checksumValue []b
 		if fn, found := checksummers[checksumType]; found {
 			checksumHash = fn()
 			checksumValue, err = hex.DecodeString(checksumValueString)
-			return
+			return checksumHash, checksumValue, err
 		}
 	}
 
-	return
+	return nil, nil, fmt.Errorf(
+		"Could not find a supported checksum in %s: %s", file, checksumType)
 }
 
 func checksumsFromFile(checksumFile string, src *url.URL) (checkSums map[string]string, err error) {
@@ -114,11 +116,15 @@ func checksumsFromFile(checksumFile string, src *url.URL) (checkSums map[string]
 			// filename matches src ?
 			if filename == option {
 				res[checksumType] = checksumValue
+				break
 			}
 		}
 
 	}
-	return
+	if len(res) == 0 {
+		err = fmt.Errorf("Could not find a checksum for %s in %s", filename, checksumFile)
+	}
+	return res, err
 }
 
 // parseChecksumLine takes a line from a checksum file and returns
@@ -150,7 +156,7 @@ func parseChecksumLine(checksumFilename, line string) (checksumType, checksumVal
 
 		for ctype := range checksummers {
 			// guess checksum type from filename
-			if strings.ContainsAny(checksumFilename, ctype) {
+			if strings.Contains(strings.ToLower(checksumFilename), ctype) {
 				checksumType = ctype
 			}
 		}
diff --git a/checksum_test.go b/checksum_test.go
index 67db982f8..ca42d0d5e 100644
--- a/checksum_test.go
+++ b/checksum_test.go
@@ -17,7 +17,7 @@ func Test_parseChecksumLine(t *testing.T) {
 	}{
 		{"gnu SHA256SUMS",
 			args{
-				"http://old-releases.ubuntu.com/releases/14.04.1/SHA256SUMS",
+				"http://old-releases.ubuntu.com/releases/14.04.1/SHA512SUMS",
 				"d9a217e80fb6dc2576d5ccca4c44376c25e6016de47a48e07345678d660fac51 *ubuntu-14.04-desktop-amd64+mac.iso",
 			},
 			"sha512",
diff --git a/source.go b/source.go
index c63f2bbaf..2c722427d 100644
--- a/source.go
+++ b/source.go
@@ -6,9 +6,9 @@ import (
 	"strings"
 )
 
-// SourceDirSubdir takes a source and returns a tuple of the URL without
-// the subdir and the URL with the subdir.
-func SourceDirSubdir(src string) (string, string) {
+// SourceDirSubdir takes a source and returns the URL without
+// the subdir and the subdir.
+func SourceDirSubdir(src string) (url string, subdir string) {
 	// Calcaulate an offset to avoid accidentally marking the scheme
 	// as the dir.
 	var offset int
@@ -16,14 +16,20 @@ func SourceDirSubdir(src string) (string, string) {
 		offset = idx + 3
 	}
 
+	// URL might contains another url in query parameters
+	stop := len(src)
+	if idx := strings.Index(src, "?"); idx > -1 {
+		stop = idx
+	}
+
 	// First see if we even have an explicit subdir
-	idx := strings.Index(src[offset:], "//")
+	idx := strings.Index(src[offset:stop], "//")
 	if idx == -1 {
 		return src, ""
 	}
 
 	idx += offset
-	subdir := src[idx+2:]
+	subdir = src[idx+2:]
 	src = src[:idx]
 
 	// Next, check if we have query parameters and push them onto the
diff --git a/source_test.go b/source_test.go
index 213324a98..c65f50f1b 100644
--- a/source_test.go
+++ b/source_test.go
@@ -28,6 +28,14 @@ func TestSourceDirSubdir(t *testing.T) {
 			"https://hashicorp.com/path//*?archive=foo",
 			"https://hashicorp.com/path?archive=foo", "*",
 		},
+		{
+			"https://hashicorp.com/path?checksum=file:http://url.com/....iso.sha256",
+			"https://hashicorp.com/path?checksum=file:http://url.com/....iso.sha256", "",
+		},
+		{
+			"https://hashicorp.com/path//*?checksum=file:http://url.com/....iso.sha256",
+			"https://hashicorp.com/path?checksum=file:http://url.com/....iso.sha256", "*",
+		},
 		{
 			"file://foo//bar",
 			"file://foo", "bar",