diff --git a/pandatool/src/eggprogs/Sources.pp b/pandatool/src/eggprogs/Sources.pp
index 23e631bf32..b759405963 100644
--- a/pandatool/src/eggprogs/Sources.pp
+++ b/pandatool/src/eggprogs/Sources.pp
@@ -3,7 +3,7 @@
 #define OTHER_LIBS \
   egg:c linmath:c putil:c express:c pandaegg:m panda:m pandaexpress:m \
   dtoolutil:c dconfig:c dtool:m pystub
-
+#define UNIX_SYS_LIBS m
 
 #begin bin_target
   #define TARGET egg-trans