diff --git a/pkgs/os-specific/darwin/apple-source-releases/libsecurity_apple_x509_tp/GNUmakefile b/pkgs/os-specific/darwin/apple-source-releases/libsecurity_apple_x509_tp/GNUmakefile
index 083a8a85d17..166b4e631c8 100644
--- a/pkgs/os-specific/darwin/apple-source-releases/libsecurity_apple_x509_tp/GNUmakefile
+++ b/pkgs/os-specific/darwin/apple-source-releases/libsecurity_apple_x509_tp/GNUmakefile
@@ -5,6 +5,7 @@ LIBRARY_NAME = security_apple_x509_tp
 security_apple_x509_tp_HEADER_FILES = $(notdir $(wildcard lib/*.h))
 security_apple_x509_tp_HEADER_FILES_DIR = lib
 
+security_apple_x509_tp_C_FILES = $(wildcard lib/*.c)
 security_apple_x509_tp_CC_FILES = $(wildcard lib/*.cpp)
 
 include $(GNUSTEP_MAKEFILES)/library.make