https://bugs.gentoo.org/792435

--- a/configure.ac
+++ b/configure.ac
@@ -106,6 +106,9 @@
 GTK_VERSION=`$PKG_CONFIG --variable=gtk_binary_version gtk+-3.0`
 AC_SUBST(GTK_VERSION)
 
+AC_CHECK_LIBM
+AC_SUBST([LIBM])
+
 # Files
 
 AC_CONFIG_FILES([
--- a/unico/Makefile.am
+++ b/unico/Makefile.am
@@ -20,6 +20,6 @@
 
 libunico_la_CFLAGS = $(UNICO_CFLAGS)
 
-libunico_la_LIBADD = $(UNICO_LIBADD)
+libunico_la_LIBADD = $(UNICO_LIBADD) $(LIBM)
 
 libunico_la_LDFLAGS = $(UNICO_LDFLAGS)
