diff --git a/src/api/dotnet/Context.cs b/src/api/dotnet/Context.cs
index 325758263..c8decb59b 100644
--- a/src/api/dotnet/Context.cs
+++ b/src/api/dotnet/Context.cs
@@ -2777,25 +2777,25 @@ namespace Microsoft.Z3
         /// <summary>
         /// Create an at-most-k constraint.
         /// </summary>
-        public BoolExpr MkAtMost(BoolExpr[] args, uint k)
+        public BoolExpr MkAtMost(IEnumerable<BoolExpr> args, uint k)
         {
            Contract.Requires(args != null);
            Contract.Requires(Contract.Result<BoolExpr[]>() != null);
            CheckContextMatch<BoolExpr>(args);
-           return new BoolExpr(this, Native.Z3_mk_atmost(nCtx, (uint) args.Length,
-                                                          AST.ArrayToNative(args), k));
+           return new BoolExpr(this, Native.Z3_mk_atmost(nCtx, (uint) args.Count(),
+                                                          AST.EnumToNative(args), k));
         }
 
         /// <summary>
         /// Create an at-least-k constraint.
         /// </summary>
-        public BoolExpr MkAtLeast(BoolExpr[] args, uint k)
+        public BoolExpr MkAtLeast(IEnumerable<BoolExpr> args, uint k)
         {
            Contract.Requires(args != null);
            Contract.Requires(Contract.Result<BoolExpr[]>() != null);
            CheckContextMatch<BoolExpr>(args);
-           return new BoolExpr(this, Native.Z3_mk_atleast(nCtx, (uint) args.Length,
-                                                          AST.ArrayToNative(args), k));
+           return new BoolExpr(this, Native.Z3_mk_atleast(nCtx, (uint) args.Count(),
+                                                          AST.EnumToNative(args), k));
         }
 
         /// <summary>
diff --git a/src/smt/theory_seq.cpp b/src/smt/theory_seq.cpp
index ef50cf3b6..51d1d7119 100644
--- a/src/smt/theory_seq.cpp
+++ b/src/smt/theory_seq.cpp
@@ -5021,7 +5021,7 @@ expr* theory_seq::coalesce_chars(expr* const& e) {
         if (bvu.is_bv(s)) {
             expr_ref result(m);
             expr * args[1] = {s};
-            if (m_seq_rewrite.mk_app_core(to_app(e)->get_decl(), 1, args, result)) {
+            if (BR_FAILED != m_seq_rewrite.mk_app_core(to_app(e)->get_decl(), 1, args, result)) {
                 if (!ctx.e_internalized(result))
                     ctx.internalize(result, false);
                 return result;
diff --git a/src/solver/smt_logics.cpp b/src/solver/smt_logics.cpp
index 7ed2b0445..5d845b78b 100644
--- a/src/solver/smt_logics.cpp
+++ b/src/solver/smt_logics.cpp
@@ -150,7 +150,7 @@ bool smt_logics::logic_has_horn(symbol const& s) {
 }
 
 bool smt_logics::logic_has_pb(symbol const& s) {
-    return s == "QF_FD" || s == "ALL";
+    return s == "QF_FD" || s == "ALL" || s == "HORN";
 }
 
 bool smt_logics::logic_has_datatype(symbol const& s) {