diff --git a/include/posix/unistd.h b/include/posix/unistd.h
index d25006a557d..fb1fe806b5c 100644
--- a/include/posix/unistd.h
+++ b/include/posix/unistd.h
@@ -21,7 +21,6 @@ extern "C" {
 #include <fs/fs.h>
 
 /* File related operations */
-extern int open(const char *name, int flags);
 extern int close(int file);
 extern ssize_t write(int file, const void *buffer, size_t count);
 extern ssize_t read(int file, void *buffer, size_t count);
diff --git a/lib/libc/minimal/include/fcntl.h b/lib/libc/minimal/include/fcntl.h
index 23028f35239..caa79c91965 100644
--- a/lib/libc/minimal/include/fcntl.h
+++ b/lib/libc/minimal/include/fcntl.h
@@ -15,4 +15,6 @@
 #define F_GETFL 3
 #define F_SETFL 4
 
+int open(const char *name, int flags);
+
 #endif /* ZEPHYR_LIB_LIBC_MINIMAL_INCLUDE_SYS_FCNTL_H_ */
diff --git a/tests/posix/common/src/mqueue.c b/tests/posix/common/src/mqueue.c
index d7123ea64e6..c83f3751fbc 100644
--- a/tests/posix/common/src/mqueue.c
+++ b/tests/posix/common/src/mqueue.c
@@ -7,6 +7,7 @@
 #include <ztest.h>
 #include <zephyr.h>
 #include <sys/printk.h>
+#include <fcntl.h>
 #include <mqueue.h>
 #include <pthread.h>
 
diff --git a/tests/posix/fs/src/test_fs_dir.c b/tests/posix/fs/src/test_fs_dir.c
index 46e4f0311f3..4b3d02ebe7c 100644
--- a/tests/posix/fs/src/test_fs_dir.c
+++ b/tests/posix/fs/src/test_fs_dir.c
@@ -5,6 +5,7 @@
  */
 
 #include <stdio.h>
+#include <fcntl.h>
 #include <posix/unistd.h>
 #include <posix/dirent.h>
 #include "test_fs.h"
diff --git a/tests/posix/fs/src/test_fs_file.c b/tests/posix/fs/src/test_fs_file.c
index 5b6036a2cc6..614f99ac47d 100644
--- a/tests/posix/fs/src/test_fs_file.c
+++ b/tests/posix/fs/src/test_fs_file.c
@@ -5,6 +5,7 @@
  */
 
 #include <string.h>
+#include <fcntl.h>
 #include <posix/unistd.h>
 #include "test_fs.h"