diff --git a/winsup/cygwin/Makefile.in b/winsup/cygwin/Makefile.in
index bcfaa2f55..bd24a96a1 100644
--- a/winsup/cygwin/Makefile.in
+++ b/winsup/cygwin/Makefile.in
@@ -220,6 +220,7 @@ MATH_OFILES:= \
 	lrintl.o \
 	lroundl.o \
 	modfl.o \
+	nanl.o \
 	nearbyint.o \
 	nearbyintf.o \
 	nearbyintl.o \
diff --git a/winsup/cygwin/common.din b/winsup/cygwin/common.din
index c2f5f0fd4..2ae3c81d3 100644
--- a/winsup/cygwin/common.din
+++ b/winsup/cygwin/common.din
@@ -894,6 +894,7 @@ munlock SIGFE
 munmap SIGFE
 nan NOSIGFE
 nanf NOSIGFE
+nanl NOSIGFE
 nanosleep SIGFE
 nearbyint NOSIGFE
 nearbyintf NOSIGFE
diff --git a/winsup/cygwin/math/nanl.c b/winsup/cygwin/math/nanl.c
new file mode 100644
index 000000000..f936b31cd
--- /dev/null
+++ b/winsup/cygwin/math/nanl.c
@@ -0,0 +1,5 @@
+long double
+nanl (const char *tagp)
+{
+  return __builtin_nanl ("");
+}