diff --git a/src/api/python/z3.py b/src/api/python/z3.py
index a2f0191cf..ee33fbe51 100644
--- a/src/api/python/z3.py
+++ b/src/api/python/z3.py
@@ -6210,7 +6210,7 @@ class Fixedpoint(Z3PPObject):
         """
         query = _get_args(query)
         sz = len(query)
-        if sz >= 1 and isinstance(query[0], FuncDecl):            
+        if sz >= 1 and isinstance(query[0], FuncDeclRef):            
             _decls = (FuncDecl * sz)()
             i = 0
             for q in query:
@@ -8340,4 +8340,4 @@ def fpToIEEEBV(x):
     """Create a Z3 floating-point conversion expression, from floating-point expression to IEEE bit-vector."""
     if __debug__:
         _z3_assert(is_fp(x), "First argument must be a Z3 floating-point expression")
-    return FPRef(Z3_mk_fpa_to_ieee_bv(x.ctx_ref(), x.ast), x.ctx)
\ No newline at end of file
+    return FPRef(Z3_mk_fpa_to_ieee_bv(x.ctx_ref(), x.ast), x.ctx)