diff --git a/bignum.c b/bignum.c
index 9eac5b26..a1360d8a 100644
--- a/bignum.c
+++ b/bignum.c
@@ -1833,7 +1833,10 @@ sexp sexp_compare (sexp ctx, sexp a, sexp b) {
     case SEXP_NUM_FIX_FLO:
       f = sexp_fixnum_to_double(a);
       g = sexp_flonum_value(b);
-      r = sexp_make_fixnum(f < g ? -1 : f == g ? 0 : 1);
+      if (isnan(g))
+        r = sexp_xtype_exception(ctx, NULL, "can't compare NaN", b);
+      else
+        r = sexp_make_fixnum(f < g ? -1 : f == g ? 0 : 1);
       break;
     case SEXP_NUM_FIX_BIG:
       if ((sexp_bignum_hi(b) > 1) ||
@@ -1845,7 +1848,12 @@ sexp sexp_compare (sexp ctx, sexp a, sexp b) {
     case SEXP_NUM_FLO_FLO:
       f = sexp_flonum_value(a);
       g = sexp_flonum_value(b);
-      r = sexp_make_fixnum(f < g ? -1 : f == g ? 0 : 1);
+      if (isnan(f))
+        r = sexp_xtype_exception(ctx, NULL, "can't compare NaN", a);
+      else if (isnan(g))
+        r = sexp_xtype_exception(ctx, NULL, "can't compare NaN", b);
+      else
+        r = sexp_make_fixnum(f < g ? -1 : f == g ? 0 : 1);
       break;
     case SEXP_NUM_FLO_BIG:
       f = sexp_flonum_value(a);
diff --git a/tests/r7rs-tests.scm b/tests/r7rs-tests.scm
index 2a7d9969..638ad115 100644
--- a/tests/r7rs-tests.scm
+++ b/tests/r7rs-tests.scm
@@ -793,6 +793,10 @@
 (test #f (<= 1 2 1))
 (test #t (>= 2 1 1))
 (test #f (>= 1 2 1))
+(test #f (< +nan.0 0))
+(test #f (> +nan.0 0))
+(test #f (< +nan.0 0.0))
+(test #f (> +nan.0 0.0))
 (test '(#t #f) (list (<= 1 1 2) (<= 2 1 3)))
 
 ;; From R7RS 6.2.6 Numerical operations:
@@ -843,6 +847,7 @@
 (test #f (positive? -1.0))
 (test #t (positive? +inf.0))
 (test #f (positive? -inf.0))
+(test #f (positive? +nan.0))
 
 (test #f (negative? 0))
 (test #f (negative? 0.0))
@@ -852,6 +857,7 @@
 (test #t (negative? -1.0))
 (test #f (negative? +inf.0))
 (test #t (negative? -inf.0))
+(test #f (negative? +nan.0))
 
 (test #f (odd? 0))
 (test #t (odd? 1))