diff --git a/project/common.mk b/project/common.mk
index af5155e..cbe8ecb 100644
--- a/project/common.mk
+++ b/project/common.mk
@@ -1,6 +1,7 @@
 libc_src_dirs       = $(SOURCE_DIR)/src/*/
 libc_src_dirs      += $(SOURCE_DIR)/crt/
 libc_src_dirs      += $(SOURCE_DIR)/ldso/
+libc_src_dirs      += $(SOURCE_DIR)/$(MALLOC_SUBDIR)/
 
 ifeq ($(PORT_DIR),$(PROJECT_DIR))
 libc_src_dirs      += $(PROJECT_DIR)/src/*/
@@ -64,6 +65,7 @@ libc_tree_dirs      = $(subst $(SOURCE_DIR)/,./,             \
 
 libc_tree_dirs     += ./crt/  ./crt/$(ARCH)/
 libc_tree_dirs     += ./ldso/ ./ldso/$(ARCH)/
+libc_tree_dirs     += $(MALLOC_SUBDIR)
 
 
 # depend on all headers
diff --git a/project/config/cfgdefs.in b/project/config/cfgdefs.in
index d8b3bb5..95db393 100644
--- a/project/config/cfgdefs.in
+++ b/project/config/cfgdefs.in
@@ -23,6 +23,9 @@ CFLAGS_CONFIG           += @libc_source_tree@
 # libgcc, libgcc_eh
 LIBC_DEPS               += @libc_deps@
 
+# mallocng */
+MALLOC_SUBDIR            = @malloc_subdir@
+
 # syscall.h
 build/syscall_h.tag:     build/@libc_syscall_arch@
 
diff --git a/project/config/cfgdefs.sh b/project/config/cfgdefs.sh
index 994ef54..a9cb7c4 100644
--- a/project/config/cfgdefs.sh
+++ b/project/config/cfgdefs.sh
@@ -126,6 +126,16 @@ cfgdefs_set_libc_cflags()
 }
 
 
+cfgdefs_set_malloc_options()
+{
+	if [ -d $mb_source_dir/src/malloc/mallocng ]; then
+		malloc_subdir='src/malloc/mallocng'
+	else
+		malloc_subdir='src/malloc/oldmalloc'
+	fi
+}
+
+
 cfgdefs_output_custom_defs()
 {
 	sed \
@@ -140,6 +150,7 @@ cfgdefs_output_custom_defs()
 			-e 's/@libc_syscall_arch@/'"$libc_syscall_arch"'/g' \
 			-e 's/@libc_td_tid_addr@/'"$libc_td_tid_addr"'/g'    \
 			-e 's!@alltypes_sed@!'"$alltypes_sed"'!g'             \
+			-e 's!@malloc_subdir@!'"$malloc_subdir"'!g'            \
 		"$mb_project_dir/project/config/cfgdefs.in"         \
 	| sed -e 's/[ \t]*$//g'                                     \
 			>> "$mb_pwd/cfgdefs.mk"
@@ -158,6 +169,9 @@ cfgdefs_set_libc_options
 # libc (variant-specific) cflags
 cfgdefs_set_libc_cflags
 
+# malloc implementation variant
+cfgdefs_set_malloc_options
+
 # cfgdefs.in --> cfgdefs.mk
 cfgdefs_output_custom_defs