diff --git a/src/classes/Makefile.PMusr b/src/classes/Makefile.PMusr
index 6e11691f..75f00df7 100644
--- a/src/classes/Makefile.PMusr
+++ b/src/classes/Makefile.PMusr
@@ -42,7 +42,7 @@ endif
 # -- Linux
 ifeq ($(OS),LINUX)
 CXX           = g++
-CXXFLAGS      = -g -Wall -Wno-trigraphs -fPIC
+CXXFLAGS      = -O3 -Wall -Wno-trigraphs -fPIC
 PMUSRPATH     = ../include
 MNPATH        = $(ROOTSYS)/include
 GSLPATH       = /usr/include/gsl