diff --git a/libc/bionic/flockfile.cpp b/libc/bionic/flockfile.cpp
index db53828..db68801 100644
--- a/libc/bionic/flockfile.cpp
+++ b/libc/bionic/flockfile.cpp
@@ -36,12 +36,20 @@
 // struct __sfileext (see fileext.h).
 
 void flockfile(FILE* fp) {
+  if (!__sdidinit) {
+    __sinit();
+  }
+
   if (fp != nullptr) {
     pthread_mutex_lock(&_FLOCK(fp));
   }
 }
 
 int ftrylockfile(FILE* fp) {
+  if (!__sdidinit) {
+    __sinit();
+  }
+
   // The specification for ftrylockfile() says it returns 0 on success,
   // or non-zero on error. So return an errno code directly on error.
   if (fp == nullptr) {
@@ -52,6 +60,10 @@
 }
 
 void funlockfile(FILE* fp) {
+  if (!__sdidinit) {
+    __sinit();
+  }
+
   if (fp != nullptr) {
     pthread_mutex_unlock(&_FLOCK(fp));
   }