diff --git a/experiment/Makefile b/experiment/Makefile
index 829cf74b..0dd4f03f 100644
--- a/experiment/Makefile
+++ b/experiment/Makefile
@@ -5,7 +5,7 @@
 
 COPT = -Wall -fpic -g -DDEBUG_LEVEL=1 -lm
 DEPS = ../floatimg.h  ../libfloatimg.a Makefile
-LIBS = ../libfloatimg.a -ltiff -lpnglite -lcfitsio
+LIBS = ../libfloatimg.a -ltiff -lpnglite -lcfitsio -lm
 
 all:	assemblage extracteur muxplanes movepixels