diff -up pbzip2-1.1.12/Makefile.flags pbzip2-1.1.12/Makefile
--- pbzip2-1.1.12/Makefile.flags	2015-09-09 16:10:11.389730644 +0200
+++ pbzip2-1.1.12/Makefile	2015-09-09 16:10:43.823872798 +0200
@@ -17,7 +17,7 @@ LDLIBS_PTHREAD = -lpthread
 
 
 # Optimization flags
-CXXFLAGS = -O2
+CXXFLAGS ?= -O2
 
 #CXXFLAGS += -g -Wall
 #CXXFLAGS += -ansi
@@ -50,11 +50,11 @@ CXXFLAGS += $(CXXFLAGS_PTHREAD)
 
 
 # Linker flags
-LDFLAGS =
+# LDFLAGS =
 
 
 # External libraries
-LDLIBS = -lbz2
+LDLIBS += -lbz2
 LDLIBS += $(LDLIBS_PTHREAD)