diff --git a/prism/ext/lp_solve_5.5_java/Makefile b/prism/ext/lp_solve_5.5_java/Makefile
index b203304e..ed9d7dcf 100644
--- a/prism/ext/lp_solve_5.5_java/Makefile
+++ b/prism/ext/lp_solve_5.5_java/Makefile
@@ -31,7 +31,7 @@ lpsolve55java:
 	@(if [ "$(OSTYPE)" = "darwin" ]; then \
 	  echo "Rebuild lpsolve55 Java wrapper for MacOS"; \
 	  pushd lib/mac/ ; \
-	  sh build-osx; \
+	  ARCH=$(ARCH) sh -x build-osx; \
 	  popd; \
 	  cp lib/lpsolve55j.jar lib/mac/liblpsolve55j.jnilib ../../lib/ ; \
 	fi)
diff --git a/prism/ext/lp_solve_5.5_java/lib/mac/build-osx b/prism/ext/lp_solve_5.5_java/lib/mac/build-osx
index 28f09236..0b583374 100755
--- a/prism/ext/lp_solve_5.5_java/lib/mac/build-osx
+++ b/prism/ext/lp_solve_5.5_java/lib/mac/build-osx
@@ -20,5 +20,12 @@ JDK_DIR=/System/Library/Frameworks/JavaVM.framework/Versions/Current/Headers
 SRC_DIR=../../src/c
 INCL="-I $JDK_DIR -I $LPSOLVE_DIR -I $SRC_DIR -idirafter /usr/include/sys"
 
-g++ -fPIC -fno-common $INCL -c $SRC_DIR/lpsolve5j.cpp
+if [ "$ARCH" = "" ]
+then
+	CFLAGS=-"arch i386 -fno-common"
+else
+	CFLAGS="-arch x86_64 -fPIC -DPIC -fno-common"
+fi
+
+g++ $CFLAGS $INCL -c $SRC_DIR/lpsolve5j.cpp
 g++ -dynamiclib lpsolve5j.o -compatibility_version 5.5.0 -current_version 5.5.0 -o liblpsolve55j.jnilib -lc -llpsolve55 -L$LPSOLVE_LIB_DIR