diff --git a/mk/spdk.lib.mk b/mk/spdk.lib.mk
index a710179d0..50429fbe6 100644
--- a/mk/spdk.lib.mk
+++ b/mk/spdk.lib.mk
@@ -36,8 +36,8 @@ include $(SPDK_ROOT_DIR)/mk/spdk.lib_deps.mk
 
 SPDK_MAP_FILE = $(SPDK_ROOT_DIR)/shared_lib/spdk.map
 LIB := $(call spdk_lib_list_to_static_libs,$(LIBNAME))
-SHARED_LINKED_LIB := $(subst .a,.so,$(LIB))
-SHARED_REALNAME_LIB := $(subst .so,.so.$(SO_SUFFIX_ALL),$(SHARED_LINKED_LIB))
+SHARED_LINKED_LIB := $(LIB:.a=.so)
+SHARED_REALNAME_LIB := $(SHARED_LINKED_LIB:.so=.so.$(SO_SUFFIX_ALL))
 
 ifeq ($(CONFIG_SHARED),y)
 DEP := $(SHARED_LINKED_LIB)