diff --git a/unittests/Expr/Makefile b/unittests/Expr/Makefile
index 5ea581b485..cfd7d0c08b 100644
--- a/unittests/Expr/Makefile
+++ b/unittests/Expr/Makefile
@@ -1,13 +1,19 @@
 ##===- unittests/Expr/Makefile -----------------------------*- Makefile -*-===##
 
 LEVEL := ../..
+include $(LEVEL)/Makefile.config
+
 TESTNAME := Expr
 STP_LIBS := stp_c_interface.a stp_AST.a stp_bitvec.a \
             stp_constantbv.a stp_sat.a stp_simplifier.a
-USEDLIBS := kleaverExpr.a kleeBasic.a $(STP_LIBS)
+USEDLIBS := kleaverExpr.a kleeBasic.a
+ifeq ($(ENABLE_EXT_STP),0)
+  USEDLIBS += $(STP_LIBS)
+endif
 LINK_COMPONENTS := support
 
-include $(LEVEL)/Makefile.config
 include $(LLVM_SRC_ROOT)/unittests/Makefile.unittest
 
-
+ifeq ($(ENABLE_EXT_STP),1)
+  LIBS += -lstp
+endif
diff --git a/unittests/Solver/Makefile b/unittests/Solver/Makefile
index 44c965ba6b..86283d24c9 100644
--- a/unittests/Solver/Makefile
+++ b/unittests/Solver/Makefile
@@ -1,13 +1,19 @@
 ##===- unittests/Solver/Makefile ---------------------------*- Makefile -*-===##
 
 LEVEL := ../..
+include $(LEVEL)/Makefile.config
+
 TESTNAME := Solver
 STP_LIBS := stp_c_interface.a stp_AST.a stp_bitvec.a \
             stp_constantbv.a stp_sat.a stp_simplifier.a
-USEDLIBS := kleaverSolver.a kleaverExpr.a kleeSupport.a kleeBasic.a $(STP_LIBS)
+USEDLIBS := kleaverSolver.a kleaverExpr.a kleeSupport.a kleeBasic.a
+ifeq ($(ENABLE_EXT_STP),0)
+  USEDLIBS += $(STP_LIBS)
+endif
 LINK_COMPONENTS := support
 
-include $(LEVEL)/Makefile.config
 include $(LLVM_SRC_ROOT)/unittests/Makefile.unittest
 
-#LIBS += -lstp 
+ifeq ($(ENABLE_EXT_STP),1)
+  LIBS += -lstp
+endif