diff --git a/mono/btls/Makefile.am b/mono/btls/Makefile.am
index 9fd47451426..de2dd081a19 100644
--- a/mono/btls/Makefile.am
+++ b/mono/btls/Makefile.am
@@ -40,6 +40,7 @@ EXTRA_DIST = $(MONO_BTLS_SOURCES_FILES)
 
 CMAKE_VERBOSE=$(if $(V),VERBOSE=1,)
 NINJA_VERBOSE=$(if ($V),-v,)
+CMAKE_AR_PROGRAM = $(shell which ar)
 
 if NINJA
 NINJA_ARGS = -G Ninja
@@ -51,7 +52,7 @@ BUILDFILE = Makefile
 CMAKE_MAKE_PROGRAM = $(shell which gmake || which gnumake || which make)
 endif
 
-CMAKE_ARGS = -D CMAKE_MAKE_PROGRAM=$(CMAKE_MAKE_PROGRAM) -D CMAKE_INSTALL_PREFIX:PATH=$(prefix) -D BTLS_ROOT:PATH=$(BTLS_ROOT) \
+CMAKE_ARGS = -D CMAKE_MAKE_PROGRAM=$(CMAKE_MAKE_PROGRAM) -D CMAKE_INSTALL_PREFIX:PATH=$(prefix) -D BTLS_ROOT:PATH=$(BTLS_ROOT) -DCMAKE_AR:PATH=$(CMAKE_AR_PROGRAM) \
 	-D SRC_DIR:PATH=$(abs_top_srcdir)/mono/btls -D BTLS_CFLAGS:STRING="$(BTLS_CFLAGS)" $(NINJA_ARGS)
 
 all-local: build-shared/libmono-btls-shared$(libsuffix)