diff --git a/src/SequenceVariation.jl b/src/SequenceVariation.jl
index 18db51a..de19df1 100644
--- a/src/SequenceVariation.jl
+++ b/src/SequenceVariation.jl
@@ -233,6 +233,10 @@ function is_valid(v::Variant)
     for edit in v.edits
         pos = edit.pos
         op = edit.x
+        # Sanity check: for this to be a valid variant, it must be comprised of valid
+        # variations
+        is_valid(Variation(v.ref, edit)) || return false
+
         # For substitutions we simply do not allow another modification of the same base
         if op isa Substitution
             pos in valid_positions || return false