diff --git a/tagcmp.go b/tagcmp.go
index 2e0183d..55d248e 100644
--- a/tagcmp.go
+++ b/tagcmp.go
@@ -144,7 +144,7 @@ func (t Tag) IsCompatible(tag Tag) bool {
 		return false
 	}
 
-	if t.Suffix != "" && tag.Suffix == "" {
+	if t.Suffix != "" && tag.Suffix == "" || t.Suffix == "" && tag.Suffix != "" {
 		return false
 	}
 
diff --git a/tagcmp_test.go b/tagcmp_test.go
index 9fb5fcd..c3af536 100644
--- a/tagcmp_test.go
+++ b/tagcmp_test.go
@@ -599,6 +599,7 @@ func TestIsCompatible(t *testing.T) {
 		{"1.2.3", "1.2.0", true},
 		{"5-alpine", "6-alpine", true},
 		{"5-alpine", "6.5-alpine", false},
+		{"5", "5-alpine", false},
 	}
 	for _, p := range pairs {
 		p1, err := tagcmp.Parse(p.t1)