diff --git a/submodules/build/builder-iphone-os.mk b/submodules/build/builder-iphone-os.mk
index 380d77b67..fa1d94d6f 100644
--- a/submodules/build/builder-iphone-os.mk
+++ b/submodules/build/builder-iphone-os.mk
@@ -193,7 +193,7 @@ build-libgsm:
 	cd $(BUILDER_BUILD_DIR)/$(gsm_dir)\
 	&& mkdir -p $(prefix)/include/gsm \
 	&& host_alias=$(host)  . $(BUILDER_SRC_DIR)/build/$(config_site) \
-	&&  make CC="$${CC}" INSTALL_ROOT=$(prefix)  GSM_INSTALL_INC=$(prefix)/include/gsm  install
+	&&  make -j1 CC="$${CC}" INSTALL_ROOT=$(prefix)  GSM_INSTALL_INC=$(prefix)/include/gsm  install
 
 clean-libgsm:
 	cd $(BUILDER_BUILD_DIR)/$(gsm_dir)\