--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -128,7 +128,7 @@
 
 rrdtool_SOURCES = rrd_tool.c
 rrdtool_DEPENDENCIES = librrd.la
-rrdtool_LDADD	= librrd.la
+rrdtool_LDADD	= librrd.la -lm
 
 rrdcached_SOURCES = rrd_daemon.c
 rrdcached_DEPENDENCIES = librrd.la librrdupd.la