diff --git a/package/speex/speex.mk b/package/speex/speex.mk
index 6d61e93833..0bbcb2bde2 100644
--- a/package/speex/speex.mk
+++ b/package/speex/speex.mk
@@ -26,6 +26,10 @@ ifeq ($(BR2_PACKAGE_SPEEX_ARM5E),y)
 SPEEX_CONF_OPTS += --enable-arm5e-asm
 endif
 
+ifeq ($(BR2_ARM_INSTRUCTIONS_THUMB),y)
+SPEEX_CONF_ENV += CFLAGS="$(TARGET_CFLAGS) -marm"
+endif
+
 define SPEEX_LIBTOOL_FIXUP
 	$(SED) 's|^hardcode_libdir_flag_spec=.*|hardcode_libdir_flag_spec=""|g' $(@D)/libtool
 	$(SED) 's|^runpath_var=LD_RUN_PATH|runpath_var=DIE_RPATH_DIE|g' $(@D)/libtool