diff --git a/contrib/10.roundtrip/emyg_dtoa.c b/contrib/10.roundtrip/emyg_dtoa.c
index 9fbc5e19..ec76a1c2 100644
--- a/contrib/10.roundtrip/emyg_dtoa.c
+++ b/contrib/10.roundtrip/emyg_dtoa.c
@@ -421,11 +421,12 @@ static inline void Prettify(char* buffer, int length, int k) {
 }
 
 void emyg_dtoa (double value, char* buffer) {
-  // Not handling NaN and inf
-  assert(!isnan(value));
-  assert(!isinf(value));
 
-  if (value == 0) {
+  if (isinf(value))
+    strcpy(buffer, signbit(value) ? "-inf.0" : "+inf.0");
+  else if (isnan(value))
+    strcpy(buffer, signbit(value) ? "-nan.0" : "+nan.0");
+  else if (value == 0) {
     buffer[0] = '0';
     buffer[1] = '.';
     buffer[2] = '0';
diff --git a/contrib/10.roundtrip/nitro.mk b/contrib/10.roundtrip/nitro.mk
index e28f3ffb..8238a1ff 100644
--- a/contrib/10.roundtrip/nitro.mk
+++ b/contrib/10.roundtrip/nitro.mk
@@ -2,3 +2,8 @@ CONTRIB_DEFS += -DPIC_CSTRING_TO_DOUBLE=emyg_atod -DPIC_DOUBLE_TO_CSTRING=emyg_d
 
 CONTRIB_SRCS += contrib/10.roundtrip/emyg_dtoa.c \
                 contrib/10.roundtrip/emyg_atod.c
+
+CONTRIB_TESTS += test-roundtrip
+
+test-roundtrip: bin/picrin
+	$(TEST_RUNNER) contrib/10.roundtrip/t/roundtrip.scm
diff --git a/contrib/10.roundtrip/t/roundtrip.scm b/contrib/10.roundtrip/t/roundtrip.scm
new file mode 100644
index 00000000..ecbde357
--- /dev/null
+++ b/contrib/10.roundtrip/t/roundtrip.scm
@@ -0,0 +1,48 @@
+(import (scheme base)
+        (srfi 27)
+        (scheme inexact)
+        (picrin test))
+
+(test-begin)
+
+(define (rountrip-ok number)
+  (let ((radix 10)) 
+    (eqv? number (string->number (number->string number radix) radix))))
+
+(test #t (rountrip-ok -nan.0))
+
+(test #t (rountrip-ok +nan.0))
+
+(test #t (rountrip-ok -inf.0))
+
+(test #t (rountrip-ok +inf.0))
+
+(test -inf.0 (string->number "-inf.0"))
+
+(test +inf.0 (string->number "+inf.0"))
+
+(test #t (nan? (string->number "-nan.0")))
+
+(test #t (nan? (string->number "+nan.0")))
+
+(define (random-roundtrip)
+  (let ((r (random-real)))
+    (if (rountrip-ok r)
+      #t
+      r)))
+
+(test #t (random-roundtrip))
+(test #t (random-roundtrip))
+(test #t (random-roundtrip))
+(test #t (random-roundtrip))
+(test #t (random-roundtrip))
+(test #t (random-roundtrip))
+(test #t (random-roundtrip))
+(test #t (random-roundtrip))
+(test #t (random-roundtrip))
+(test #t (random-roundtrip))
+(test #t (random-roundtrip))
+(test #t (random-roundtrip))
+(test #t (random-roundtrip))
+
+(test-end)