diff --git a/src/ast/fpa/fpa2bv_converter.cpp b/src/ast/fpa/fpa2bv_converter.cpp
index 9ecac1ec9..b4c346170 100644
--- a/src/ast/fpa/fpa2bv_converter.cpp
+++ b/src/ast/fpa/fpa2bv_converter.cpp
@@ -2946,8 +2946,11 @@ void fpa2bv_converter::mk_to_ieee_bv(func_decl * f, unsigned num, expr * const *
 
     expr_ref sig_unspec(s, m);
     if (sbits > 2)
-        sig_unspec = m_bv_util.mk_concat(mk_to_ieee_bv_unspecified(sbits - 2),
-                                         m_bv_util.mk_numeral(1, 1));
+        sig_unspec = m_bv_util.mk_concat(
+            mk_to_ieee_bv_unspecified(sbits - 2),
+            m_bv_util.mk_numeral(1, 1));
+    else
+        sig_unspec = m_bv_util.mk_numeral(1, 1);
 
     result = m_bv_util.mk_concat(m_bv_util.mk_concat(sgn, e), m.mk_ite(x_is_nan, sig_unspec, s));
 }
diff --git a/src/ast/rewriter/fpa_rewriter.cpp b/src/ast/rewriter/fpa_rewriter.cpp
index 8352e14ce..5d9175259 100644
--- a/src/ast/rewriter/fpa_rewriter.cpp
+++ b/src/ast/rewriter/fpa_rewriter.cpp
@@ -158,8 +158,15 @@ br_status fpa_rewriter::mk_to_ieee_bv_unspecified(func_decl * f, expr_ref & resu
     if (m_hi_fp_unspecified)
         // The "hardware interpretation" is 0.
         result = bu.mk_numeral(0, bv_sz);
-    else
-        result = m_util.mk_internal_to_ieee_bv_unspecified(bv_sz);
+    else {
+        unsigned sbits = m_util.get_sbits(f->get_domain()[0]);
+
+        if (sbits > 2)
+            result = bu.mk_concat(m_util.mk_internal_to_ieee_bv_unspecified(sbits - 2),
+                                  bu.mk_numeral(1, 1));
+        else
+            result = bu.mk_numeral(1, 1);
+    }
 
     return BR_DONE;
 }
@@ -863,16 +870,17 @@ br_status fpa_rewriter::mk_to_ieee_bv(func_decl * f, expr * arg, expr_ref & resu
 
     if (m_util.is_numeral(arg, v)) {
 
-        if (m_fm.is_nan(v) || m_fm.is_inf(v)) {
+        if (m_fm.is_nan(v)) {
             mk_to_ieee_bv_unspecified(f, result);
             return BR_REWRITE_FULL;
         }
-
-        bv_util bu(m());
-        scoped_mpz rz(m_fm.mpq_manager());
-        m_fm.to_ieee_bv_mpz(v, rz);
-        result = bu.mk_numeral(rational(rz), v.get().get_ebits() + v.get().get_sbits());
-        return BR_DONE;
+        else {
+            bv_util bu(m());
+            scoped_mpz rz(m_fm.mpq_manager());
+            m_fm.to_ieee_bv_mpz(v, rz);
+            result = bu.mk_numeral(rational(rz), v.get().get_ebits() + v.get().get_sbits());
+            return BR_DONE;
+        }
     }
 
     return BR_FAILED;
diff --git a/src/util/mpf.cpp b/src/util/mpf.cpp
index 1d7ed1bb3..5de4c406a 100644
--- a/src/util/mpf.cpp
+++ b/src/util/mpf.cpp
@@ -1190,18 +1190,28 @@ void mpf_manager::to_sbv_mpq(mpf_rounding_mode rm, const mpf & x, scoped_mpq & o
 }
 
 void mpf_manager::to_ieee_bv_mpz(const mpf & x, scoped_mpz & o) {
-    SASSERT(!is_nan(x) && !is_inf(x));
+    SASSERT(!is_nan(x));
     SASSERT(exp(x) < INT_MAX);
 
     unsigned sbits = x.get_sbits();
     unsigned ebits = x.get_ebits();
-    scoped_mpz biased_exp(m_mpz_manager);
-    m_mpz_manager.set(biased_exp, bias_exp(ebits, exp(x)));
-    m_mpz_manager.set(o, sgn(x));
-    m_mpz_manager.mul2k(o, ebits);
-    m_mpz_manager.add(o, biased_exp, o);
-    m_mpz_manager.mul2k(o, sbits - 1);
-    m_mpz_manager.add(o, sig(x), o);
+
+    if (is_inf(x)) {
+        m_mpz_manager.set(o, sgn(x));
+        m_mpz_manager.mul2k(o, ebits);
+        const mpz & exp = m_powers2.m1(ebits);
+        m_mpz_manager.add(o, exp, o);
+        m_mpz_manager.mul2k(o, sbits - 1);
+    }
+    else {
+        scoped_mpz biased_exp(m_mpz_manager);
+        m_mpz_manager.set(biased_exp, bias_exp(ebits, exp(x)));
+        m_mpz_manager.set(o, sgn(x));
+        m_mpz_manager.mul2k(o, ebits);
+        m_mpz_manager.add(o, biased_exp, o);
+        m_mpz_manager.mul2k(o, sbits - 1);
+        m_mpz_manager.add(o, sig(x), o);
+    }
 }
 
 void mpf_manager::rem(mpf const & x, mpf const & y, mpf & o) {