diff --git a/libc/config/gpu/entrypoints.txt b/libc/config/gpu/entrypoints.txt
index 4fb87cb9f5a33e..4af2e0b727a2b5 100644
--- a/libc/config/gpu/entrypoints.txt
+++ b/libc/config/gpu/entrypoints.txt
@@ -179,6 +179,7 @@ set(TARGET_LIBC_ENTRYPOINTS
     libc.src.stdio.ferror
     libc.src.stdio.fseek
     libc.src.stdio.fflush
+    libc.src.stdio.fileno
     libc.src.stdio.ftell
     libc.src.stdio.clearerr
     libc.src.stdio.puts
diff --git a/libc/config/linux/aarch64/entrypoints.txt b/libc/config/linux/aarch64/entrypoints.txt
index a48a94f715eb7e..58502e4ec1c660 100644
--- a/libc/config/linux/aarch64/entrypoints.txt
+++ b/libc/config/linux/aarch64/entrypoints.txt
@@ -542,6 +542,7 @@ if(LLVM_LIBC_FULL_BUILD)
     libc.src.stdio.ferror_unlocked
     libc.src.stdio.fgetc
     libc.src.stdio.fflush
+    libc.src.stdio.fileno
     libc.src.stdio.fopen
     libc.src.stdio.fputc
     libc.src.stdio.fputs
diff --git a/libc/config/linux/riscv/entrypoints.txt b/libc/config/linux/riscv/entrypoints.txt
index 5e28378b403a79..d789f03fedc419 100644
--- a/libc/config/linux/riscv/entrypoints.txt
+++ b/libc/config/linux/riscv/entrypoints.txt
@@ -565,6 +565,7 @@ if(LLVM_LIBC_FULL_BUILD)
     libc.src.stdio.fgetc_unlocked
     libc.src.stdio.fgets
     libc.src.stdio.fflush
+    libc.src.stdio.fileno
     libc.src.stdio.fopen
     libc.src.stdio.fputc
     libc.src.stdio.fputs
diff --git a/libc/test/src/stdio/CMakeLists.txt b/libc/test/src/stdio/CMakeLists.txt
index 6e1c86e070a823..3ccce16a76a2d5 100644
--- a/libc/test/src/stdio/CMakeLists.txt
+++ b/libc/test/src/stdio/CMakeLists.txt
@@ -14,6 +14,7 @@ add_libc_test(
     libc.src.stdio.feof
     libc.src.stdio.ferror
     libc.src.stdio.fflush
+    libc.src.stdio.fileno
     libc.src.stdio.fopen
     libc.src.stdio.fputs
     libc.src.stdio.fread
diff --git a/libc/test/src/stdio/fileop_test.cpp b/libc/test/src/stdio/fileop_test.cpp
index 2f2e63eaf75d4c..0fbe19cf08d837 100644
--- a/libc/test/src/stdio/fileop_test.cpp
+++ b/libc/test/src/stdio/fileop_test.cpp
@@ -11,6 +11,7 @@
 #include "src/stdio/feof.h"
 #include "src/stdio/ferror.h"
 #include "src/stdio/fflush.h"
+#include "src/stdio/fileno.h"
 #include "src/stdio/fopen.h"
 #include "src/stdio/fputs.h"
 #include "src/stdio/fread.h"