--- plug-ins/retinex/Makefile.am.orig
+++ plug-ins/retinex/Makefile.am
@@ -20,7 +20,7 @@
 	$(X_LIBS) \
         $(top_builddir)/libhalf/cinepaint_half.lo       \
         $(OPENEXR_LIBS) \
-	-lc
+	-lm
 
 DEPS = $(top_builddir)/lib/libcinepaint.la