diff --git a/src/stub/src/amd64-linux.elf-so_main.c b/src/stub/src/amd64-linux.elf-so_main.c
index b76f1070..67ceab11 100644
--- a/src/stub/src/amd64-linux.elf-so_main.c
+++ b/src/stub/src/amd64-linux.elf-so_main.c
@@ -37,7 +37,6 @@ extern unsigned Pprotect(void *, size_t, unsigned);
 extern void *Pmap(void *, size_t, unsigned, unsigned, int, size_t);
 extern int Punmap(void *, size_t);
 extern size_t Pwrite(unsigned, void const *, size_t);
-extern int ftruncate(int fd, off_t length);
 
 extern void f_int3(int arg);
 
diff --git a/src/stub/src/i386-linux.elf-so_main.c b/src/stub/src/i386-linux.elf-so_main.c
index de7fd20d..c79afea7 100644
--- a/src/stub/src/i386-linux.elf-so_main.c
+++ b/src/stub/src/i386-linux.elf-so_main.c
@@ -298,7 +298,6 @@ make_hatch_i386(
 #elif defined(__arm__)  /*}{*/
 extern unsigned get_sys_munmap(void);
 extern int upxfd_create(void);  // early 32-bit Android lacks memfd_create
-extern size_t lseek(int fd, size_t offset, int whence);
 #define SEEK_SET 0
 
 static void *
diff --git a/src/stub/src/i386-linux.elf.execve-main.c b/src/stub/src/i386-linux.elf.execve-main.c
index 0fb6c784..6d8842e3 100644
--- a/src/stub/src/i386-linux.elf.execve-main.c
+++ b/src/stub/src/i386-linux.elf.execve-main.c
@@ -127,9 +127,6 @@ static uint32_t ascii5(char *p, uint32_t v, unsigned n)
 }
 
 
-extern char *mmap(void *addr, size_t len,
-    int prot, int flags, int fd, off_t offset);
-
 #if defined(__i386__)
 #  define SET2(p, c0, c1) \
         * (unsigned short *) (p) = ((c1)<<8 | (c0))
diff --git a/src/stub/src/i386-linux.elf.interp-main.c b/src/stub/src/i386-linux.elf.interp-main.c
index bee4603b..72abc3fb 100644
--- a/src/stub/src/i386-linux.elf.interp-main.c
+++ b/src/stub/src/i386-linux.elf.interp-main.c
@@ -96,9 +96,6 @@ do_brk(void *addr)
     return brk(addr);
 }
 
-extern char *mmap(void *addr, size_t len,
-    int prot, int flags, int fd, off_t offset);
-
 /*************************************************************************
 // UPX & NRV stuff
 **************************************************************************/
diff --git a/src/stub/src/i386-linux.elf.shell-main.c b/src/stub/src/i386-linux.elf.shell-main.c
index d8987c56..5cf98702 100644
--- a/src/stub/src/i386-linux.elf.shell-main.c
+++ b/src/stub/src/i386-linux.elf.shell-main.c
@@ -93,9 +93,6 @@ do_brk(void *addr)
     return brk(addr);
 }
 
-extern char *mmap(void *addr, size_t len,
-    int prot, int flags, int fd, off_t offset);
-
 /*************************************************************************
 // UPX & NRV stuff
 **************************************************************************/
diff --git a/src/stub/src/include/linux.h b/src/stub/src/include/linux.h
index 5d458863..932272b7 100644
--- a/src/stub/src/include/linux.h
+++ b/src/stub/src/include/linux.h
@@ -546,8 +546,9 @@ static ssize_t write(int fd, void const *buf, size_t len)
 void *brk(void *);
 int close(int);
 void exit(int) __attribute__((__noreturn__,__nothrow__));
+int ftruncate(int fd, size_t len);
+off_t lseek(int fd, off_t offset, int whence);
 int memfd_create(char const *, unsigned);
-void *mmap(void *, size_t, int, int, int, off_t);
 int munmap(void *, size_t);
 int mprotect(void const *, size_t, int);
 int open(char const *, unsigned, unsigned);
@@ -557,6 +558,7 @@ ssize_t write(int, void const *, size_t);
 
 #endif  /*}*/
 void __clear_cache(void *, void *);
+void *mmap(void *, size_t, int, int, int, off_t);
 
 
 /*************************************************************************