--- a/library-src/makefile.lnx
+++ b/library-src/makefile.lnx
@@ -9,7 +9,12 @@
 # Notes:
 #    -fPIC option needed for 64-bit systems
 
-all: ubuntu
+all: libCLIPSJNI.so
+
+CC ?=
+CFLAGS ?=
+JAVA_HOME ?=
+LDFLAGS ?=
 
 ubuntu : JAVA_HOME = /usr/lib/jvm/default-java
 ubuntu : libCLIPSJNI.so
@@ -63,7 +68,7 @@ OBJS = agenda.o analysis.o argacces.o bload.o bmathfun.o bsave.o \
  	clipsjni_utilities.o clipsjni_glue.o
 
 .c.o :
-	gcc -c -std=c99 -O3 -fPIC -DLINUX \
+	$(CC) -c -std=c99 -fPIC $(CFLAGS) $(LDFLAGS) -DLINUX \
 	    -I$(JAVA_INCLUDE) -I$(JAVA_INCLUDE_OS) \
 	    -fno-strict-aliasing -Wstrict-aliasing \
 	    -Wall -Wundef -Wpointer-arith -Wshadow \
@@ -72,7 +77,7 @@ OBJS = agenda.o analysis.o argacces.o bload.o bmathfun.o bsave.o \
 	    -Wstrict-prototypes -Waggregate-return -Wno-implicit $<
 
 libCLIPSJNI.so : $(OBJS) 
-	gcc -o libCLIPSJNI.so -fPIC -shared \
+	$(CC) -o libCLIPSJNI.so -fPIC $(CFLAGS) $(LDFLAGS) -shared \
 		-lm $(OBJS) 
 
 clean :