diff --git a/src/api/python/z3.py b/src/api/python/z3.py
index 0626d2f3c..323e57c79 100644
--- a/src/api/python/z3.py
+++ b/src/api/python/z3.py
@@ -9095,6 +9095,10 @@ def _coerce_seq(s, ctx=None):
     if isinstance(s, str):
         ctx = _get_ctx(ctx)
         s = StringVal(s, ctx)
+    if not is_expr(s):
+        raise Z3Exception("Non-expression passed as a sequence")
+    if not is_seq(s):
+        raise Z3Exception("Non-sequence passed as a sequence")
     return s
 
 def _get_ctx2(a, b, ctx=None):