diff --git a/datacoin-qt.pro b/datacoin-qt.pro
index f531607..df0ecc4 100644
--- a/datacoin-qt.pro
+++ b/datacoin-qt.pro
@@ -4,7 +4,7 @@ macx:TARGET = "Datacoin-Qt"
 VERSION = 0.8.3
 INCLUDEPATH += src src/json src/qt
 QT += network
-DEFINES += QT_GUI BOOST_THREAD_USE_LIB BOOST_SPIRIT_THREADSAFE
+DEFINES += QT_GUI BOOST_THREAD_USE_LIB BOOST_SPIRIT_THREADSAFE LEVELDB_WITHOUT_MEMENV
 CONFIG += no_include_pwd
 CONFIG += thread
 
@@ -104,25 +104,29 @@ contains(BITCOIN_NEED_QT_PLUGINS, 1) {
     QTPLUGIN += qcncodecs qjpcodecs qtwcodecs qkrcodecs qtaccessiblewidgets
 }
 
+contains(USE_SYSTEM_LEVELDB, 1) {
+    LIBS += -lleveldb
+} else {
 INCLUDEPATH += src/leveldb/include src/leveldb/helpers
-LIBS += $$PWD/src/leveldb/libleveldb.a $$PWD/src/leveldb/libmemenv.a
+LIBS += $$PWD/src/leveldb/libleveldb.a
 !win32 {
     # we use QMAKE_CXXFLAGS_RELEASE even without RELEASE=1 because we use RELEASE to indicate linking preferences not -O preferences
-    genleveldb.commands = cd $$PWD/src/leveldb && CC=$$QMAKE_CC CXX=$$QMAKE_CXX $(MAKE) OPT=\"$$QMAKE_CXXFLAGS $$QMAKE_CXXFLAGS_RELEASE\" libleveldb.a libmemenv.a
+    genleveldb.commands = cd $$PWD/src/leveldb && CC=$$QMAKE_CC CXX=$$QMAKE_CXX $(MAKE) OPT=\"$$QMAKE_CXXFLAGS $$QMAKE_CXXFLAGS_RELEASE\" libleveldb.a
 } else {
     # make an educated guess about what the ranlib command is called
     isEmpty(QMAKE_RANLIB) {
         QMAKE_RANLIB = $$replace(QMAKE_STRIP, strip, ranlib)
     }
     LIBS += -lshlwapi
-    genleveldb.commands = cd $$PWD/src/leveldb && CC=$$QMAKE_CC CXX=$$QMAKE_CXX TARGET_OS=OS_WINDOWS_CROSSCOMPILE $(MAKE) OPT=\"$$QMAKE_CXXFLAGS $$QMAKE_CXXFLAGS_RELEASE\" libleveldb.a libmemenv.a && $$QMAKE_RANLIB $$PWD/src/leveldb/libleveldb.a && $$QMAKE_RANLIB $$PWD/src/leveldb/libmemenv.a
+    genleveldb.commands = cd $$PWD/src/leveldb && CC=$$QMAKE_CC CXX=$$QMAKE_CXX TARGET_OS=OS_WINDOWS_CROSSCOMPILE $(MAKE) OPT=\"$$QMAKE_CXXFLAGS $$QMAKE_CXXFLAGS_RELEASE\" libleveldb.a && $$QMAKE_RANLIB $$PWD/src/leveldb/libleveldb.a
 }
 genleveldb.target = $$PWD/src/leveldb/libleveldb.a
 genleveldb.depends = FORCE
 PRE_TARGETDEPS += $$PWD/src/leveldb/libleveldb.a
 QMAKE_EXTRA_TARGETS += genleveldb
+}
 # Gross ugly hack that depends on qmake internals, unfortunately there is no other way to do it.
-QMAKE_CLEAN += $$PWD/src/leveldb/libleveldb.a; cd $$PWD/src/leveldb ; $(MAKE) clean
+QMAKE_CLEAN += $$PWD/src/leveldb/libleveldb.a; cd $$PWD/src/leveldb && $(MAKE) clean || true
 
 # regenerate src/build.h
 !win32|contains(USE_BUILD_INFO, 1) {
diff --git a/src/leveldb.cpp b/src/leveldb.cpp
index e66f851..2856d70 100644
--- a/src/leveldb.cpp
+++ b/src/leveldb.cpp
@@ -8,7 +8,9 @@
 #include <leveldb/env.h>
 #include <leveldb/cache.h>
 #include <leveldb/filter_policy.h>
-#include <memenv/memenv.h>
+#ifndef LEVELDB_WITHOUT_MEMENV
+#include <memenv.h>
+#endif
 
 #include <boost/filesystem.hpp>
 
@@ -43,8 +45,12 @@ CLevelDB::CLevelDB(const boost::filesystem::path &path, size_t nCacheSize, bool
     options = GetOptions(nCacheSize);
     options.create_if_missing = true;
     if (fMemory) {
+#ifndef LEVELDB_WITHOUT_MEMENV
         penv = leveldb::NewMemEnv(leveldb::Env::Default());
         options.env = penv;
+#else
+	throw std::runtime_error("CLevelDB(): compiled without memenv support");
+#endif
     } else {
         if (fWipe) {
             printf("Wiping LevelDB in %s\n", path.string().c_str());
diff --git a/src/makefile.unix b/src/makefile.unix
index 359ac3d..ec1e075 100644
--- a/src/makefile.unix
+++ b/src/makefile.unix
@@ -120,8 +120,7 @@ xCXXFLAGS=-O2 -pthread -Wall -Wextra -Wformat -Wformat-security -Wno-unused-para
 # adds some defaults in front. Unfortunately, LDFLAGS=... $(LDFLAGS) does not work.
 xLDFLAGS=$(LDHARDENING) $(LDFLAGS)
 
-OBJS= \
-    leveldb/libleveldb.a \
+BASEOBJS := \
     obj/alert.o \
     obj/version.o \
     obj/checkpoints.o \
@@ -130,7 +129,6 @@ OBJS= \
     obj/crypter.o \
     obj/key.o \
     obj/db.o \
-    obj/init.o \
     obj/keystore.o \
     obj/main.o \
     obj/net.o \
@@ -150,25 +148,44 @@ OBJS= \
     obj/hash.o \
     obj/bloom.o \
     obj/noui.o \
-    obj/leveldb.o \
     obj/txdb.o \
     obj/prime.o \
     obj/checkpointsync.o
 
+OBJS := \
+    obj/leveldb.o \
+    obj/init.o \
+    $(BASEOBJS)
+
+TESTOBJS := \
+    obj-test/leveldb.o \
+    $(patsubst test/%.cpp,obj-test/%.o,$(wildcard test/*.cpp)) \
+    $(BASEOBJS)
+
 all: datacoind
 
 test check: test_primecoin FORCE
 	./test_primecoin
 
+ifdef USE_SYSTEM_LEVELDB
+    LIBS += -lleveldb
+    TESTLIBS += -lmemenv
+else
 #
 # LevelDB support
 #
 MAKEOVERRIDES =
-LIBS += $(CURDIR)/leveldb/libleveldb.a $(CURDIR)/leveldb/libmemenv.a
+LIBS += $(CURDIR)/leveldb/libleveldb.a
+TESTLIBS += $(CURDIR)/leveldb/libmemenv.a
 DEFS += $(addprefix -I,$(CURDIR)/leveldb/include)
 DEFS += $(addprefix -I,$(CURDIR)/leveldb/helpers)
 leveldb/libleveldb.a:
-	@echo "Building LevelDB ..." && cd leveldb && $(MAKE) CC=$(CC) CXX=$(CXX) OPT="$(xCXXFLAGS)" libleveldb.a libmemenv.a && cd ..
+	@echo "Building LevelDB ..." && cd leveldb && $(MAKE) CC=$(CC) CXX=$(CXX) OPT="$(xCXXFLAGS)" libleveldb.a && cd ..
+leveldb/libmemenv.a:
+	@echo "Building LevelDB memenv ..." && cd leveldb && $(MAKE) CC=$(CC) CXX=$(CXX) OPT="$(xCXXFLAGS)" libmemenv.a && cd ..
+OBJS += leveldb/libleveldb.a
+TESTOBJS += leveldb/libmemenv.a
+endif
 
 # auto-generated dependencies:
 -include obj/*.P
@@ -179,24 +196,22 @@ obj/build.h: FORCE
 version.cpp: obj/build.h
 DEFS += -DHAVE_BUILD_INFO
 
-obj/%.o: %.cpp
-	$(CXX) -c $(xCXXFLAGS) -MMD -MF $(@:%.o=%.d) -o $@ $<
+P_TO_D = \
 	@cp $(@:%.o=%.d) $(@:%.o=%.P); \
-	  sed -e 's/#.*//' -e 's/^[^:]*: *//' -e 's/ *\\$$//' \
+	    sed -e 's/\#.*//' -e 's/^[^:]*: *//' -e 's/ *\\$$//' \
 	      -e '/^$$/ d' -e 's/$$/ :/' < $(@:%.o=%.d) >> $(@:%.o=%.P); \
 	  rm -f $(@:%.o=%.d)
 
-datacoind: $(OBJS:obj/%=obj/%)
-	$(LINK) $(xCXXFLAGS) -o $@ $^ $(xLDFLAGS) $(LIBS)
+obj/%.o: %.cpp
+	$(CXX) -c $(xCXXFLAGS) -DLEVELDB_WITHOUT_MEMENV -MMD -MF $(@:%.o=%.d) -o $@ $<
+	$(P_TO_D)
 
-TESTOBJS := $(patsubst test/%.cpp,obj-test/%.o,$(wildcard test/*.cpp))
+datacoind: $(OBJS)
+	$(LINK) $(xCXXFLAGS) -o $@ $^ $(xLDFLAGS) $(LIBS)
 
 obj-test/%.o: test/%.cpp
-	$(CXX) -c $(TESTDEFS) $(xCXXFLAGS) -MMD -MF $(@:%.o=%.d) -o $@ $<
-	@cp $(@:%.o=%.d) $(@:%.o=%.P); \
-	  sed -e 's/#.*//' -e 's/^[^:]*: *//' -e 's/ *\\$$//' \
-	      -e '/^$$/ d' -e 's/$$/ :/' < $(@:%.o=%.d) >> $(@:%.o=%.P); \
-	  rm -f $(@:%.o=%.d)
+	$(CXX) -c $(xCXXFLAGS) -DLEVELDB_WITHOUT_MEMENV -MMD -MF $(@:%.o=%.d) -o $@ $<
+	$(P_TO_D)
 
 test_primecoin: $(TESTOBJS) $(filter-out obj/init.o,$(OBJS:obj/%=obj/%))
 	$(LINK) $(xCXXFLAGS) -o $@ $(LIBPATHS) $^ $(TESTLIBS) $(xLDFLAGS) $(LIBS)