diff --git a/bignum.c b/bignum.c
index 79a86c89..8c5d298d 100644
--- a/bignum.c
+++ b/bignum.c
@@ -1528,7 +1528,16 @@ sexp sexp_compare (sexp ctx, sexp a, sexp b) {
       r = sexp_make_fixnum(f < g ? -1 : f == g ? 0 : 1);
       break;
     case SEXP_NUM_FLO_BIG:
-      a = tmp = sexp_double_to_bignum(ctx, sexp_flonum_value(a));
+      f = sexp_flonum_value(a);
+      if (isinf(f)) {
+        r = f > 0 ? SEXP_ONE : SEXP_NEG_ONE;
+        break;
+      } else if (isnan(f)) {
+        r = sexp_xtype_exception(ctx, NULL, "can't compare NaN", a);
+        break;
+      } else {
+        a = tmp = sexp_double_to_bignum(ctx, f);
+      }
       /* ... FALLTHROUGH ... */
     case SEXP_NUM_BIG_BIG:
       r = sexp_make_fixnum(sexp_bignum_compare(a, b));
@@ -1536,8 +1545,14 @@ sexp sexp_compare (sexp ctx, sexp a, sexp b) {
 #if SEXP_USE_RATIOS
     case SEXP_NUM_FLO_RAT:
       f = sexp_flonum_value(a);
-      g = sexp_ratio_to_double(b);
-      r = sexp_make_fixnum(f < g ? -1 : f == g ? 0 : 1);
+      if (isinf(f)) {
+        r = f > 0 ? SEXP_ONE : SEXP_NEG_ONE;
+      } else if (isnan(f)) {
+        r = sexp_xtype_exception(ctx, NULL, "can't compare NaN", a);
+      } else {
+        g = sexp_ratio_to_double(b);
+        r = sexp_make_fixnum(f < g ? -1 : f == g ? 0 : 1);
+      }
       break;
     case SEXP_NUM_FIX_RAT:
     case SEXP_NUM_BIG_RAT:
diff --git a/vm.c b/vm.c
index 3cad0810..82804225 100644
--- a/vm.c
+++ b/vm.c
@@ -1750,8 +1750,14 @@ sexp sexp_apply (sexp ctx, sexp proc, sexp args) {
       _ARG1 = sexp_make_boolean(i);
     } else {
       _ARG1 = sexp_compare(ctx, tmp1, tmp2);
-      sexp_check_exception();
-      _ARG1 = sexp_make_boolean(sexp_unbox_fixnum(_ARG1) < 0);
+      if (sexp_exceptionp(_ARG1)) {
+        if (strcmp("can't compare NaN", sexp_string_data(sexp_exception_message(_ARG1))) == 0)
+          _ARG1 = SEXP_FALSE;
+        else
+          goto call_error_handler;
+      } else {
+        _ARG1 = sexp_make_boolean(sexp_unbox_fixnum(_ARG1) < 0);
+      }
     }
 #else
 #if SEXP_USE_FLONUMS
@@ -1775,8 +1781,14 @@ sexp sexp_apply (sexp ctx, sexp proc, sexp args) {
       _ARG1 = sexp_make_boolean(i);
     } else {
       _ARG1 = sexp_compare(ctx, tmp1, tmp2);
-      sexp_check_exception();
-      _ARG1 = sexp_make_boolean(sexp_unbox_fixnum(_ARG1) <= 0);
+      if (sexp_exceptionp(_ARG1)) {
+        if (strcmp("can't compare NaN", sexp_string_data(sexp_exception_message(_ARG1))) == 0)
+          _ARG1 = SEXP_FALSE;
+        else
+          goto call_error_handler;
+      } else {
+        _ARG1 = sexp_make_boolean(sexp_unbox_fixnum(_ARG1) <= 0);
+      }
     }
 #else
 #if SEXP_USE_FLONUMS
@@ -1828,8 +1840,14 @@ sexp sexp_apply (sexp ctx, sexp proc, sexp args) {
 #endif
       /* neither is complex */
       _ARG1 = sexp_compare(ctx, tmp1, tmp2);
-      sexp_check_exception();
-      _ARG1 = sexp_make_boolean(_ARG1 == SEXP_ZERO);
+      if (sexp_exceptionp(_ARG1)) {
+        if (strcmp("can't compare NaN", sexp_string_data(sexp_exception_message(_ARG1))) == 0)
+          _ARG1 = SEXP_FALSE;
+        else
+          goto call_error_handler;
+      } else {
+        _ARG1 = sexp_make_boolean(_ARG1 == SEXP_ZERO);
+      }
     }
 #else
 #if SEXP_USE_FLONUMS