diff --git a/mongoose.h b/mongoose.h
index e14694f0..80db5e6b 100644
--- a/mongoose.h
+++ b/mongoose.h
@@ -219,7 +219,7 @@ static inline void *mg_calloc(size_t cnt, size_t size) {
   return p;
 }
 
-#if MG_ENABLE_POSIX_FS
+#if !defined(MG_ENABLE_POSIX_FS) || !MG_ENABLE_POSIX_FS
 #else
 #define mkdir(a, b) mg_mkdir(a, b)
 static inline int mg_mkdir(const char *path, mode_t mode) {
diff --git a/src/arch_freertos.h b/src/arch_freertos.h
index cbf7ba9b..7443e69f 100644
--- a/src/arch_freertos.h
+++ b/src/arch_freertos.h
@@ -37,7 +37,7 @@ static inline void *mg_calloc(size_t cnt, size_t size) {
   return p;
 }
 
-#if MG_ENABLE_POSIX_FS
+#if !defined(MG_ENABLE_POSIX_FS) || !MG_ENABLE_POSIX_FS
 #else
 #define mkdir(a, b) mg_mkdir(a, b)
 static inline int mg_mkdir(const char *path, mode_t mode) {