diff --git a/src/ast/float_decl_plugin.cpp b/src/ast/float_decl_plugin.cpp
index 21d4d6a86..4aab6ab32 100644
--- a/src/ast/float_decl_plugin.cpp
+++ b/src/ast/float_decl_plugin.cpp
@@ -256,6 +256,7 @@ func_decl * float_decl_plugin::mk_unary_rel_decl(decl_kind k, unsigned num_param
     case OP_FLOAT_IS_NZERO: name = "isNZero";   break;
     case OP_FLOAT_IS_PZERO: name = "isPZero";   break;        
     case OP_FLOAT_IS_SIGN_MINUS: name = "isSignMinus";  break;
+    case OP_FLOAT_IS_NAN: name = "isNaN";  break;
     case OP_FLOAT_IS_INF: name = "isInfinite";  break;
     case OP_FLOAT_IS_NORMAL: name = "isNormal";  break;
     case OP_FLOAT_IS_SUBNORMAL: name = "isSubnormal";  break;
@@ -418,6 +419,7 @@ func_decl * float_decl_plugin::mk_func_decl(decl_kind k, unsigned num_parameters
     case OP_FLOAT_IS_NZERO:
     case OP_FLOAT_IS_PZERO:
     case OP_FLOAT_IS_SIGN_MINUS: 
+    case OP_FLOAT_IS_NAN:
     case OP_FLOAT_IS_INF:
     case OP_FLOAT_IS_NORMAL:
     case OP_FLOAT_IS_SUBNORMAL:
@@ -479,6 +481,7 @@ void float_decl_plugin::get_op_names(svector<builtin_name> & op_names, symbol co
     op_names.push_back(builtin_name("<=", OP_FLOAT_LE));
     op_names.push_back(builtin_name(">=", OP_FLOAT_GE));
 
+    op_names.push_back(builtin_name("isNaN", OP_FLOAT_IS_NAN));
     op_names.push_back(builtin_name("isInfinite", OP_FLOAT_IS_INF));
     op_names.push_back(builtin_name("isZero", OP_FLOAT_IS_ZERO));
     op_names.push_back(builtin_name("isNZero", OP_FLOAT_IS_NZERO));
diff --git a/src/ast/float_decl_plugin.h b/src/ast/float_decl_plugin.h
index fd632a8a1..f1b60a91b 100644
--- a/src/ast/float_decl_plugin.h
+++ b/src/ast/float_decl_plugin.h
@@ -61,6 +61,7 @@ enum float_op_kind {
     OP_FLOAT_GT,
     OP_FLOAT_LE,
     OP_FLOAT_GE,
+    OP_FLOAT_IS_NAN,
     OP_FLOAT_IS_INF,
     OP_FLOAT_IS_ZERO,
     OP_FLOAT_IS_NORMAL,
@@ -240,6 +241,7 @@ public:
     app * mk_le(expr * arg1, expr * arg2) { return m().mk_app(m_fid, OP_FLOAT_LE, arg1, arg2); }
     app * mk_ge(expr * arg1, expr * arg2) { return m().mk_app(m_fid, OP_FLOAT_GE, arg1, arg2); }
 
+    app * mk_is_nan(expr * arg1) { return m().mk_app(m_fid, OP_FLOAT_IS_NAN, arg1); }
     app * mk_is_inf(expr * arg1) { return m().mk_app(m_fid, OP_FLOAT_IS_INF, arg1); }
     app * mk_is_zero(expr * arg1) { return m().mk_app(m_fid, OP_FLOAT_IS_ZERO, arg1); }
     app * mk_is_normal(expr * arg1) { return m().mk_app(m_fid, OP_FLOAT_IS_NORMAL, arg1); }
diff --git a/src/ast/rewriter/float_rewriter.cpp b/src/ast/rewriter/float_rewriter.cpp
index bfcfbcbfc..015bce0ed 100644
--- a/src/ast/rewriter/float_rewriter.cpp
+++ b/src/ast/rewriter/float_rewriter.cpp
@@ -58,6 +58,7 @@ br_status float_rewriter::mk_app_core(func_decl * f, unsigned num_args, expr * c
     case OP_FLOAT_IS_ZERO:   SASSERT(num_args == 1); st = mk_is_zero(args[0], result); break;
     case OP_FLOAT_IS_NZERO:  SASSERT(num_args == 1); st = mk_is_nzero(args[0], result); break;
     case OP_FLOAT_IS_PZERO:  SASSERT(num_args == 1); st = mk_is_pzero(args[0], result); break;
+    case OP_FLOAT_IS_NAN:    SASSERT(num_args == 1); st = mk_is_nan(args[0], result); break;
     case OP_FLOAT_IS_INF:    SASSERT(num_args == 1); st = mk_is_inf(args[0], result); break;
     case OP_FLOAT_IS_NORMAL: SASSERT(num_args == 1); st = mk_is_normal(args[0], result); break;
     case OP_FLOAT_IS_SUBNORMAL: SASSERT(num_args == 1); st = mk_is_subnormal(args[0], result); break;
@@ -431,6 +432,16 @@ br_status float_rewriter::mk_is_pzero(expr * arg1, expr_ref & result) {
     return BR_FAILED;
 }
 
+br_status float_rewriter::mk_is_nan(expr * arg1, expr_ref & result) {
+    scoped_mpf v(m_util.fm());
+    if (m_util.is_value(arg1, v)) {
+        result = (m_util.fm().is_nan(v)) ? m().mk_true() : m().mk_false();
+        return BR_DONE;
+    }
+
+    return BR_FAILED;
+}
+
 br_status float_rewriter::mk_is_inf(expr * arg1, expr_ref & result) {
     scoped_mpf v(m_util.fm());
     if (m_util.is_value(arg1, v)) {
diff --git a/src/ast/rewriter/float_rewriter.h b/src/ast/rewriter/float_rewriter.h
index 6968d96cf..4a0879d4b 100644
--- a/src/ast/rewriter/float_rewriter.h
+++ b/src/ast/rewriter/float_rewriter.h
@@ -66,6 +66,7 @@ public:
     br_status mk_is_zero(expr * arg1, expr_ref & result);
     br_status mk_is_nzero(expr * arg1, expr_ref & result);
     br_status mk_is_pzero(expr * arg1, expr_ref & result);
+    br_status mk_is_nan(expr * arg1, expr_ref & result);
     br_status mk_is_inf(expr * arg1, expr_ref & result);
     br_status mk_is_normal(expr * arg1, expr_ref & result);
     br_status mk_is_subnormal(expr * arg1, expr_ref & result);
diff --git a/src/tactic/fpa/fpa2bv_converter.cpp b/src/tactic/fpa/fpa2bv_converter.cpp
index d95709813..dd40e8453 100644
--- a/src/tactic/fpa/fpa2bv_converter.cpp
+++ b/src/tactic/fpa/fpa2bv_converter.cpp
@@ -1621,6 +1621,11 @@ void fpa2bv_converter::mk_is_pzero(func_decl * f, unsigned num, expr * const * a
     m_simp.mk_and(a0_is_pos, a0_is_zero, result);
 }
 
+void fpa2bv_converter::mk_is_nan(func_decl * f, unsigned num, expr * const * args, expr_ref & result) {
+    SASSERT(num == 1);
+    mk_is_nan(args[0], result);
+}
+
 void fpa2bv_converter::mk_is_inf(func_decl * f, unsigned num, expr * const * args, expr_ref & result) {
     SASSERT(num == 1);
     mk_is_inf(args[0], result);
diff --git a/src/tactic/fpa/fpa2bv_converter.h b/src/tactic/fpa/fpa2bv_converter.h
index 9f9c74c38..821618bae 100644
--- a/src/tactic/fpa/fpa2bv_converter.h
+++ b/src/tactic/fpa/fpa2bv_converter.h
@@ -116,6 +116,7 @@ public:
     void mk_is_nzero(func_decl * f, unsigned num, expr * const * args, expr_ref & result);
     void mk_is_pzero(func_decl * f, unsigned num, expr * const * args, expr_ref & result);
     void mk_is_sign_minus(func_decl * f, unsigned num, expr * const * args, expr_ref & result);
+    void mk_is_nan(func_decl * f, unsigned num, expr * const * args, expr_ref & result);
     void mk_is_inf(func_decl * f, unsigned num, expr * const * args, expr_ref & result);
     void mk_is_normal(func_decl * f, unsigned num, expr * const * args, expr_ref & result);
     void mk_is_subnormal(func_decl * f, unsigned num, expr * const * args, expr_ref & result);
diff --git a/src/tactic/fpa/fpa2bv_rewriter.h b/src/tactic/fpa/fpa2bv_rewriter.h
index 59d068626..24e275c0d 100644
--- a/src/tactic/fpa/fpa2bv_rewriter.h
+++ b/src/tactic/fpa/fpa2bv_rewriter.h
@@ -132,6 +132,7 @@ struct fpa2bv_rewriter_cfg : public default_rewriter_cfg {
             case OP_FLOAT_IS_ZERO: m_conv.mk_is_zero(f, num, args, result); return BR_DONE;
             case OP_FLOAT_IS_NZERO: m_conv.mk_is_nzero(f, num, args, result); return BR_DONE;
             case OP_FLOAT_IS_PZERO: m_conv.mk_is_pzero(f, num, args, result); return BR_DONE;
+            case OP_FLOAT_IS_NAN: m_conv.mk_is_nan(f, num, args, result); return BR_DONE;
             case OP_FLOAT_IS_INF: m_conv.mk_is_inf(f, num, args, result); return BR_DONE;
             case OP_FLOAT_IS_NORMAL: m_conv.mk_is_normal(f, num, args, result); return BR_DONE;
             case OP_FLOAT_IS_SUBNORMAL: m_conv.mk_is_subnormal(f, num, args, result); return BR_DONE;