diff --git a/.cirrus.yml b/.cirrus.yml
index 06d058d3..5cc1d1a6 100644
--- a/.cirrus.yml
+++ b/.cirrus.yml
@@ -6,9 +6,7 @@ freebsd_task:
     OPAMYES: 1
   env:
     matrix:
-      - OCAML_VERSION: 4.12.1
-      - OCAML_VERSION: 4.13.0
-      - OCAML_VERSION: 4.13.1
+      - OCAML_VERSION: 5.0.0
   pkg_install_script: pkg install -y ocaml-opam gmp gmake pkgconf bash
   opam_ocaml_cache:
     folder: $HOME/.opam
diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
index ba1bf581..d00d5563 100644
--- a/.github/workflows/test.yml
+++ b/.github/workflows/test.yml
@@ -5,7 +5,7 @@ jobs:
     strategy:
       matrix:
         operating-system: [ubuntu-latest]
-        ocaml-version: [4.13.1]
+        ocaml-version: [5.0.0]
         mode:
           - name: hvt
             exec: false
@@ -17,17 +17,6 @@ jobs:
             exec: false
           - name: xen
             exec: false
-        include:
-          - operating-system: ubuntu-latest
-            ocaml-version: 4.13.0
-            mode:
-              name: spt
-              exec: true
-          - operating-system: ubuntu-latest
-            ocaml-version: 4.12.1
-            mode:
-              name: spt
-              exec: true
     runs-on: ${{ matrix.operating-system }}
     steps:
     - uses: actions/checkout@v2
diff --git a/Makefile b/Makefile
index e819259a..dbe1e869 100644
--- a/Makefile
+++ b/Makefile
@@ -11,7 +11,7 @@ LOCAL_CFLAGS=$(MAKECONF_CFLAGS) -I$(TOP)/nolibc/include -include _solo5/override
 # CFLAGS used by the OCaml compiler to build C stubs
 GLOBAL_CFLAGS=$(MAKECONF_CFLAGS) -I$(MAKECONF_PREFIX)/solo5-sysroot/include/nolibc/ -include _solo5/overrides.h
 # LIBS used by the OCaml compiler to link executables
-GLOBAL_LIBS=-L$(MAKECONF_PREFIX)/solo5-sysroot/lib/nolibc/ -lnolibc -lopenlibm $(MAKECONF_EXTRA_LIBS)
+GLOBAL_LIBS=-L$(MAKECONF_PREFIX)/solo5-sysroot/lib/nolibc/ -Wl,--start-group -lnolibc -lopenlibm $(MAKECONF_EXTRA_LIBS) -Wl,--end-group
 
 # NOLIBC
 NOLIBC_CFLAGS=$(LOCAL_CFLAGS) -I$(TOP)/openlibm/src -I$(TOP)/openlibm/include
@@ -45,28 +45,43 @@ ocaml/Makefile:
 # 	configure link test
 # - We override OCAML_OS_TYPE since configure just hardcodes it to "Unix".
 OC_CFLAGS=$(LOCAL_CFLAGS) -I$(TOP)/openlibm/include -I$(TOP)/openlibm/src -nostdlib
-OC_LIBS=-L$(TOP)/nolibc -lnolibc -L$(TOP)/openlibm -lopenlibm -nostdlib $(MAKECONF_EXTRA_LIBS)
+OC_LIBS=-L$(TOP)/nolibc -lnolibc -L$(TOP)/openlibm -Wl,--start-group -lopenlibm -nostdlib $(MAKECONF_EXTRA_LIBS) -Wl,--end-group
 ocaml/Makefile.config: ocaml/Makefile openlibm/libopenlibm.a nolibc/libnolibc.a
 # configure: Do not build dynlink
-	sed -i -e 's/otherlibraries="dynlink"/otherlibraries=""/g' ocaml/configure
+	sed -e 's/otherlibraries="dynlink"/otherlibraries=""/g' ocaml/configure > ocaml/configure.sed && \
+		mv ocaml/configure.sed ocaml/configure
 # configure: Allow precise input of flags and libs
-	sed -i -e 's/oc_cflags="/oc_cflags="$$OC_CFLAGS /g' ocaml/configure
-	sed -i -e 's/ocamlc_cflags="/ocamlc_cflags="$$OCAMLC_CFLAGS /g' ocaml/configure
-	sed -i -e 's/nativecclibs="$$cclibs $$DLLIBS"/nativecclibs="$$GLOBAL_LIBS"/g' ocaml/configure
-# runtime/Makefile: Runtime rules: don't build libcamlrun.a and import ocamlrun from the system
-	sed -i -e 's/^all: $$(BYTECODE_STATIC_LIBRARIES) $$(BYTECODE_SHARED_LIBRARIES)/all: primitives ld.conf/' ocaml/runtime/Makefile
-	sed -i -e 's/^ocamlrun$$(EXE):.*/dummy:/g' ocaml/runtime/Makefile
-	sed -i -e 's/^ocamlruni$$(EXE):.*/dummyi:/g' ocaml/runtime/Makefile
-	sed -i -e 's/^ocamlrund$$(EXE):.*/dummyd:/g' ocaml/runtime/Makefile
-	echo -e "ocamlrun:\n\tcp $(shell which ocamlrun) .\n" >> ocaml/runtime/Makefile
-	echo -e "ocamlrund:\n\tcp $(shell which ocamlrund) .\n" >> ocaml/runtime/Makefile
-	echo -e "ocamlruni:\n\tcp $(shell which ocamlruni) .\n" >> ocaml/runtime/Makefile
-	touch ocaml/runtime/libcamlrun.a ocaml/runtime/libcamlrund.a ocaml/runtime/libcamlruni.a
+	sed -e 's/oc_cflags="/oc_cflags="$$OC_CFLAGS /g' ocaml/configure > ocaml/configure.sed && \
+		mv ocaml/configure.sed ocaml/configure
+	sed -e 's/ocamlc_cflags="/ocamlc_cflags="$$OCAMLC_CFLAGS /g' ocaml/configure > ocaml/configure.sed && \
+		mv ocaml/configure.sed ocaml/configure
+	sed -e 's/nativecclibs="$$cclibs $$DLLIBS $$PTHREAD_LIBS"/nativecclibs="$$GLOBAL_LIBS"/g' ocaml/configure > ocaml/configure.sed && \
+		mv ocaml/configure.sed ocaml/configure
+	sed -e 's/^arch=none$$/arch=$(MAKECONF_OCAML_BUILD_ARCH)/' ocaml/configure > ocaml/configure.sed && \
+		mv ocaml/configure.sed ocaml/configure
+	chmod +x ocaml/configure
+# Makefile: Runtime rules: don't build libcamlrun.a and import ocamlrun from the system
+	sed -e 's/^ocamlrun$$(EXE):.*/dummy:/g' ocaml/Makefile > ocaml/Makefile.sed && \
+		mv ocaml/Makefile.sed ocaml/Makefile
+	sed -e 's/^ocamlruni$$(EXE):.*/dummyi:/g' ocaml/Makefile > ocaml/Makefile.sed && \
+		mv ocaml/Makefile.sed ocaml/Makefile
+	sed -e 's/^ocamlrund$$(EXE):.*/dummyd:/g' ocaml/Makefile > ocaml/Makefile.sed && \
+		mv ocaml/Makefile.sed ocaml/Makefile
+	sed -e 's,^coldstart: $(COLDSTART_DEPS)$$,coldstart: runtime/primitives $$(COLDSTART_DEPS),' ocaml/Makefile > ocaml/Makefile.sed && \
+		mv ocaml/Makefile.sed ocaml/Makefile
+	echo -e "ocamlrun:\n\tcp $(shell which ocamlrun) .\n" >> ocaml/Makefile
+	echo -e "ocamlrund:\n\tcp $(shell which ocamlrund) .\n" >> ocaml/Makefile
+	echo -e "ocamlruni:\n\tcp $(shell which ocamlruni) .\n" >> ocaml/Makefile
+	echo -e "runtime/ocamlrun\$$(EXE):\n\tcp $(shell which ocamlrun) runtime/\n" >> ocaml/Makefile
+	echo -e "runtime/ocamlrund\$$(EXE):\n\tcp $(shell which ocamlrund) runtime/\n" >> ocaml/Makefile
+	echo -e "runtime/ocamlruni\$$(EXE):\n\tcp $(shell which ocamlruni) runtime/\n" >> ocaml/Makefile
 # yacc/Makefile: import ocamlyacc from the system
-	sed -i -e 's/^ocamlyacc$$(EXE):.*/dummy:/g' ocaml/yacc/Makefile
-	echo -e "ocamlyacc:\n\tcp $(shell which ocamlyacc) .\n" >> ocaml/yacc/Makefile
-# tools/Makefile: stub out objinfo_helper
-	echo -e "objinfo_helper:\n\ttouch objinfo_helper\n" >> ocaml/tools/Makefile
+	sed -e 's,^$$(ocamlyacc_PROGRAM)$$(EXE):.*,dummy_yacc:,g' ocaml/Makefile > ocaml/Makefile.sed && \
+		mv ocaml/Makefile.sed ocaml/Makefile
+	echo -e "\$$(ocamlyacc_PROGRAM)\$$(EXE):\n\tcp $(shell which ocamlyacc) yacc/\n" >> ocaml/Makefile
+# patch ocaml 5.0.0 runtime for single domain/thread solo5
+	sed -e 's/#define Max_domains 128/#define Max_domains 1/' ocaml/runtime/caml/domain.h > ocaml/runtime/caml/domain.h.sed && \
+		mv ocaml/runtime/caml/domain.h.sed ocaml/runtime/caml/domain.h
 # av_cv_libm_cos=no is passed to configure to prevent -lm being used (which
 # would use the host system libm instead of the freestanding openlibm, see
 # https://github.com/mirage/ocaml-solo5/issues/101
@@ -89,10 +104,11 @@ ocaml/Makefile.config: ocaml/Makefile openlibm/libopenlibm.a nolibc/libnolibc.a
 		-disable-systhreads\
 		-disable-unix-lib\
 		-disable-instrumented-runtime\
+		-disable-debug-runtime\
 		-disable-ocamltest\
 		-disable-ocamldoc\
 		$(MAKECONF_OCAML_CONFIGURE_OPTIONS)
-	echo "ARCH=$(MAKECONF_OCAML_BUILD_ARCH)" >> ocaml/Makefile.config
+	echo 'NATIVE_COMPILER=true' >> ocaml/Makefile.config
 	echo 'SAK_CC=cc' >> ocaml/Makefile.config
 	echo 'SAK_CFLAGS=' >> ocaml/Makefile.config
 	echo 'SAK_LINK=cc $(SAK_CFLAGS) $$(OUTPUTEXE)$$(1) $$(2)' >> ocaml/Makefile.config
diff --git a/README.md b/README.md
index 04e2536b..ef5ee075 100644
--- a/README.md
+++ b/README.md
@@ -71,8 +71,7 @@ Run: `solo5-hvt _build/default.solo5/main.exe`
 
 ## Supported compiler versions
 
-Tested against OCaml 4.12.1 through 4.13.0. Other versions may require
-changing `configure.sh`.
+Tested against OCaml 5.0. Other versions may require changing `configure.sh`.
 
 ## Porting to a different (uni)kernel base layer
 
diff --git a/example/startup.c b/example/startup.c
index cde67ab7..263eddb3 100644
--- a/example/startup.c
+++ b/example/startup.c
@@ -10,4 +10,5 @@ void _nolibc_init(uintptr_t heap_start, size_t heap_size); // defined in nolibc/
 int solo5_app_main(const struct solo5_start_info *si) {
     _nolibc_init(si->heap_start, si->heap_size);
     caml_startup(unused_argv);
+    return 0;
 }
diff --git a/nolibc/Makefile b/nolibc/Makefile
index 4294f2cf..6f8f4c3e 100644
--- a/nolibc/Makefile
+++ b/nolibc/Makefile
@@ -21,9 +21,11 @@ OBJS=assert.o \
      dtoa.o \
      memchr.o memcmp.o memcpy.o memmove.o memset.o \
      strcmp.o strlen.o strtol.o strchr.o strchrnul.o strncpy.o stpncpy.o \
-     strstr.o strncmp.o \
+     strstr.o strncmp.o puts.o \
      stubs.o \
-     vfprintf.o vsnprintf.o snprintf.o fprintf.o printf.o
+     vfprintf.o vsnprintf.o snprintf.o fprintf.o printf.o \
+     sysconf.o \
+     mmap.o
 
 dtoa.o: CFLAGS+=-fno-strict-aliasing
 
@@ -42,15 +44,15 @@ TEST_H_OBJS=$(patsubst %.h,test-%.o,$(HEADERS))
 
 # For each HEADER we want to test, generate a C source file including only
 # that HEADER. As above, HEADER may include subdirectories.
-test-include/%.c: include/%.h | test-include/sys
+test-include/%.c: include/%.h | test-include/sys/
 	echo "#include \"../$<\"" >$@
 
 .PRECIOUS: test-include/%.c
 
-test-include:
-	mkdir $@
+test-include/:
+	mkdir -p $@
 
-test-include/sys: test-include
-	mkdir $@
+test-include/sys/: test-include/
+	mkdir -p $@
 
-test-headers: $(TEST_H_OBJS)
+test-headers: test-include/sys/ $(TEST_H_OBJS)
diff --git a/nolibc/assert.c b/nolibc/assert.c
index dcdcd1fc..ae89be31 100644
--- a/nolibc/assert.c
+++ b/nolibc/assert.c
@@ -1,17 +1,11 @@
 #include <stdlib.h>
-#include <string.h>
-#include <unistd.h>
+#include <stdio.h>
 
 /*
  * These functions deliberately do not call printf() or malloc() in order to
  * abort as quickly as possible without triggering further errors.
  */
 
-static void puts(const char *s)
-{
-    (void)write(2, s, strlen(s));
-}
-
 void _assert_fail(const char *file, const char *line, const char *e)
 {
     puts(file);
diff --git a/nolibc/include/ctype.h b/nolibc/include/ctype.h
index 354a9a70..71aab003 100644
--- a/nolibc/include/ctype.h
+++ b/nolibc/include/ctype.h
@@ -6,5 +6,7 @@ int isdigit(int);
 int isprint(int);
 int isspace(int);
 int isupper(int);
+int isalnum(int);
+int tolower(int);
 
 #endif
diff --git a/nolibc/include/errno.h b/nolibc/include/errno.h
index 67c3b760..fedbe481 100644
--- a/nolibc/include/errno.h
+++ b/nolibc/include/errno.h
@@ -10,5 +10,9 @@ extern int errno;
 #define EINVAL 6
 #define ENOMEM 7
 #define EMFILE 8
+#define EBUSY 9
+/* TODO(dinosaure): we probably should follow the Cosmopolitan
+ * project about these constants and use values where we have
+ * an {unix,bsd} consensus. */
 
 #endif
diff --git a/nolibc/include/fcntl.h b/nolibc/include/fcntl.h
index a291d292..fd45d996 100644
--- a/nolibc/include/fcntl.h
+++ b/nolibc/include/fcntl.h
@@ -9,5 +9,9 @@ int open(const char *, int, ...);
 #define O_CREAT (1<<3)
 #define O_TRUNC (1<<4)
 #define O_EXCL (1<<5)
+#define O_RDWR (1<<6)
+/* TODO(dinosaure): same as errno values, we should take a
+ * look on the Cosmopolitan project and set values when
+ * we can find an {unix,bsd} consensus. */
 
 #endif
diff --git a/nolibc/include/pthread.h b/nolibc/include/pthread.h
new file mode 100644
index 00000000..ea7b5651
--- /dev/null
+++ b/nolibc/include/pthread.h
@@ -0,0 +1,57 @@
+#ifndef _PTHREAD_H
+#define _PTHREAD_H
+
+#include <stddef.h>
+#include <signal.h>
+
+typedef unsigned long int pthread_t;
+typedef int cpu_set_t;
+
+int pthread_getaffinity_np(pthread_t, size_t, cpu_set_t *);
+
+pthread_t pthread_self(void);
+
+typedef int pthread_attr_t;
+
+int pthread_create(pthread_t *, const pthread_attr_t *, void *(*)(void *), void *);
+int pthread_join(pthread_t, void **);
+int pthread_attr_init(pthread_attr_t *);
+void pthread_cleanup_push(void (*)(void *), void *);
+void pthread_cleanup_pop(int);
+
+typedef int pthread_mutex_t;
+typedef int pthread_cond_t;
+
+int pthread_mutex_lock(pthread_mutex_t *);
+int pthread_mutex_trylock(pthread_mutex_t *);
+int pthread_mutex_unlock(pthread_mutex_t *);
+
+#define PTHREAD_MUTEX_INITIALIZER 0
+#define PTHREAD_COND_INITIALIZER 0
+
+int pthread_sigmask(int, const sigset_t *, sigset_t *);
+int pthread_detach(pthread_t);
+int pthread_equal(pthread_t, pthread_t);
+
+typedef int pthread_mutexattr_t;
+
+int pthread_mutexattr_init(pthread_mutexattr_t *);
+int pthread_mutexattr_settype(pthread_mutexattr_t *, int);
+
+#define PTHREAD_MUTEX_ERRORCHECK 0
+
+int pthread_mutex_init(pthread_mutex_t *, const pthread_mutexattr_t *);
+int pthread_mutexattr_destroy(pthread_mutexattr_t *);
+int pthread_mutex_destroy(pthread_mutex_t *);
+
+typedef int pthread_condattr_t;
+
+int pthread_condattr_init(pthread_condattr_t *);
+int pthread_cond_init(pthread_cond_t *, const pthread_condattr_t *);
+
+int pthread_cond_wait(pthread_cond_t *, pthread_mutex_t *);
+int pthread_cond_broadcast(pthread_cond_t *);
+int pthread_cond_signal(pthread_cond_t *);
+int pthread_cond_destroy(pthread_cond_t *);
+
+#endif
diff --git a/nolibc/include/sched.h b/nolibc/include/sched.h
new file mode 100644
index 00000000..e5fa9302
--- /dev/null
+++ b/nolibc/include/sched.h
@@ -0,0 +1,8 @@
+#ifndef _SCHED_H
+#define _SCHED_H
+
+typedef int cpu_set_t;
+
+#define CPU_ZERO (x) 0
+
+#endif
diff --git a/nolibc/include/setjmp.h b/nolibc/include/setjmp.h
index 2e602dad..4d079b5d 100644
--- a/nolibc/include/setjmp.h
+++ b/nolibc/include/setjmp.h
@@ -1 +1,5 @@
 #include <signal.h>
+
+void longjmp(int, int) __attribute__ ((__noreturn__));
+
+#define setjmp(buf) 0
diff --git a/nolibc/include/signal.h b/nolibc/include/signal.h
index 53fa89f3..5d0a9d55 100644
--- a/nolibc/include/signal.h
+++ b/nolibc/include/signal.h
@@ -4,14 +4,24 @@
 typedef int jmp_buf;
 int setjmp(jmp_buf);
 void (*signal(int sig, void (*func)(int)))(int);
-#define SIG_DFL NULL
-#define SIG_IGN NULL
-#define SIG_ERR NULL
+#define SIG_DFL 0
+#define SIG_IGN 0
+#define SIG_ERR 0
+#define SIG_BLOCK 0
+#define SIG_SETMASK 0
 /*
  * The following definitions are not required by the OCaml runtime, but are
  * needed to build the freestanding version of GMP used by Mirage.
+ * For OCaml 5.0.0, it's not totally true. SIG_{BLOCK,SETMASK,IGN,DFL) are
+ * needed by the OCaml runtime.
+ *
+ * NOTE: Solo5 does not implement signals, but we should not trigger
+ * a situation where these values are really used.
  */
 #define SIGFPE 1
 int raise(int);
 
+typedef int sigset_t;
+int sigfillset(sigset_t *);
+
 #endif
diff --git a/nolibc/include/stdatomic.h b/nolibc/include/stdatomic.h
new file mode 100644
index 00000000..6ab87ddd
--- /dev/null
+++ b/nolibc/include/stdatomic.h
@@ -0,0 +1,69 @@
+#ifndef _STDATOMIC_H
+#define _STDATOMIC_H
+
+// Compatibility with non-clang compilers
+#ifndef __has_builtin
+#  define __has_builtin(x) 0
+#endif
+
+#define atomic_load_explicit(x, mode) ( *x )
+#define atomic_load(x) ( *x )
+
+extern int memory_order_release;
+extern int memory_order_acquire;
+extern int memory_order_relaxed;
+extern int memory_order_seq_cst;
+
+#if __has_builtin(__c11_atomic_fetch_add)
+#define atomic_fetch_add(X, Y) __c11_atomic_fetch_add(X, Y, __ATOMIC_SEQ_CST)
+#else
+#define atomic_fetch_add(X, Y) ({ __auto_type tmp = *X; *X = tmp + Y; tmp; })
+#endif
+
+#define atomic_fetch_add_explicit(X, Y, MOD) atomic_fetch_add(X, Y)
+
+#define atomic_thread_fence(MO) do {} while (0)
+
+typedef unsigned long long atomic_uint_fast64_t;
+
+#if __has_builtin(__c11_atomic_compare_exchange_strong)
+#define atomic_compare_exchange_strong(OBJ, EXPECTED, DESIRED) \
+	__c11_atomic_compare_exchange_strong(OBJ, EXPECTED, DESIRED, \
+			__ATOMIC_SEQ_CST, __ATOMIC_SEQ_CST)
+#else
+#define atomic_compare_exchange_strong(OBJ, EXPECTED, DESIRED) \
+  ({ int ret = 0; \
+     if (*OBJ == *EXPECTED) { \
+       *OBJ = DESIRED; \
+       ret = 1; \
+     } \
+     ret; \
+  })
+#endif
+
+#if __has_builtin(__c11_atomic_exchange)
+#define atomic_exchange(OBJ, DESIRED) \
+	__c11_atomic_exchange(OBJ, DESIRED, __ATOMIC_SEQ_CST)
+#else
+#define atomic_exchange(OBJ, DESIRED) \
+  ({ __auto_type tmp = *OBJ; \
+     *OBJ = DESIRED; \
+     tmp; \
+  })
+#endif
+
+#define atomic_store(OBJ, DESIRED) do { *OBJ = DESIRED; } while(0)
+#define atomic_store_explicit(OBJ, DESIRED, ORDER) atomic_store(OBJ, DESIRED)
+
+#if __has_builtin(__c11_atomic_fetch_or)
+#define atomic_fetch_or(OBJ, ARG) \
+	__c11_atomic_fetch_or(OBJ, ARG, __ATOMIC_SEQ_CST)
+#else
+#define atomic_fetch_or(OBJ, ARG) \
+  ({ __auto_type tmp = *OBJ; \
+     *OBJ = *OBJ | ARG; \
+     tmp; \
+  })
+#endif
+
+#endif
diff --git a/nolibc/include/stdio.h b/nolibc/include/stdio.h
index 43b959e0..0754a18e 100644
--- a/nolibc/include/stdio.h
+++ b/nolibc/include/stdio.h
@@ -33,5 +33,10 @@ size_t fwrite(const void *, size_t, size_t, FILE *);
 int fputc(int, FILE *);
 int putc(int, FILE *);
 int ferror(FILE *);
+int fputs(const char *, FILE *);
+FILE *fopen(const char *, const char *);
+int fclose(FILE *);
+int puts(const char *);
+int putchar(int);
 
 #endif
diff --git a/nolibc/include/stdlib.h b/nolibc/include/stdlib.h
index 9f890036..e7949749 100644
--- a/nolibc/include/stdlib.h
+++ b/nolibc/include/stdlib.h
@@ -31,4 +31,9 @@ int system(const char *);
 double strtod(const char *, char **);
 long strtol(const char *, char **, int);
 
+void qsort(void *base, size_t nmemb, size_t size,
+           int (*compare)(const void *, const void *));
+
+char *mktemp(char *);
+
 #endif
diff --git a/nolibc/include/string.h b/nolibc/include/string.h
index 10fb3619..226325e5 100644
--- a/nolibc/include/string.h
+++ b/nolibc/include/string.h
@@ -16,6 +16,7 @@ char *strerror(int);
  * needed to build the freestanding version of GMP used by Mirage.
  */
 char *strncpy(char *, const char *, size_t);
+char *strcpy(char *, const char *);
 char *strchr(const char *, int);
 char *strstr(const char *, const char *);
 /*
@@ -23,4 +24,9 @@ char *strstr(const char *, const char *);
  */
 int strncmp(const char*, const char*, size_t);
 
+/* TODO(dinosaure): we must track where they are used to know if we need
+ * to implement them or not. */
+int strerror_r(int errnum, char *buf, size_t buflen);
+char *strdup(const char *);
+
 #endif
diff --git a/nolibc/include/sys/mman.h b/nolibc/include/sys/mman.h
new file mode 100644
index 00000000..59bd8a2e
--- /dev/null
+++ b/nolibc/include/sys/mman.h
@@ -0,0 +1,25 @@
+#ifndef _MMAP_H
+#define _MMAP_H
+
+#include <stddef.h>
+#include <sys/types.h>
+
+void *mmap(void *addr, size_t len, int prot, int flags, int fildes, off_t off);
+
+#define PROT_NONE 0
+#define PROT_READ 1
+#define PROT_WRITE 2
+
+#define MAP_SHARED 0x01
+#define MAP_PRIVATE 0x02
+#define MAP_FIXED 0x10
+#define MAP_ANONYMOUS 0x20
+#define MAP_ANON MAP_ANONYMOUS
+
+#define MAP_FAILED NULL
+
+#define OCAML_SOLO5_PAGESIZE (1 << 12)
+
+int munmap(void *addr, size_t len);
+
+#endif
diff --git a/nolibc/include/sys/stat.h b/nolibc/include/sys/stat.h
index 3f0ddffb..cf4d4a59 100644
--- a/nolibc/include/sys/stat.h
+++ b/nolibc/include/sys/stat.h
@@ -11,7 +11,10 @@ struct stat {
 #define S_IFMT 0
 #define S_IFREG 0
 #define S_ISREG(x) (0)
+#define S_IRUSR 0
+#define S_IWUSR 0
 int stat(const char *, struct stat *);
 int mkdir(const char *, mode_t);
+int fstat(int, struct stat *);
 
 #endif
diff --git a/nolibc/include/sys/types.h b/nolibc/include/sys/types.h
index a916f597..af8bcacb 100644
--- a/nolibc/include/sys/types.h
+++ b/nolibc/include/sys/types.h
@@ -8,5 +8,6 @@ typedef int pid_t;
 typedef int off_t;
 typedef int ssize_t;
 typedef int mode_t;
+typedef int useconds_t;
 
 #endif
diff --git a/nolibc/include/unistd.h b/nolibc/include/unistd.h
index 479e6fcf..cbedb7a3 100644
--- a/nolibc/include/unistd.h
+++ b/nolibc/include/unistd.h
@@ -15,5 +15,11 @@ ssize_t write(int, const void *, size_t);
 ssize_t readlink(const char *, char *, size_t);
 int unlink(const char *);
 int rmdir(const char *);
+int usleep(useconds_t);
+int ftruncate(int, off_t);
+long sysconf(int);
+
+#define _SC_PAGESIZE 1
+#define _SC_PAGE_SIZE _SC_PAGESIZE
 
 #endif
diff --git a/nolibc/mmap.c b/nolibc/mmap.c
new file mode 100644
index 00000000..03ca1f96
--- /dev/null
+++ b/nolibc/mmap.c
@@ -0,0 +1,35 @@
+#include <stdlib.h>
+#include <stdio.h>
+
+#include <sys/mman.h>
+
+void *mmap(void *addr, size_t len, int prot, int flags, int fildes, off_t off) {
+
+  /* man page for mmap says:
+   * If addr is not NULL, then the kernel takes it as a hint about where to place
+   * the mapping; [...] If another apping already exists there, the kernel picks
+   * a new address that may or *may not* depend on the hint.
+   *
+   * XXX(dinosaure): for our purpose (Solo5 & OCaml), OCaml does not require a
+   * specific (aligned) address from [mmap]. We can use [malloc()] instead of.
+   * The OCaml usage of [mmap()] is only to allocate some spaces, only [fildes
+   * == -1] is handled so.
+   */
+  (void)addr;
+  (void)prot;
+  if (fildes != -1) {
+    printf("mmap: file descriptor is unsupported.\n");
+    abort();
+  }
+  if (!(flags & MAP_ANONYMOUS) || off != 0) {
+    printf("mmap: only MAP_ANONYMOUS (and offset is 0) is supported.\n");
+    abort();
+  }
+
+  void *ptr = NULL;
+  posix_memalign(&ptr, OCAML_SOLO5_PAGESIZE, len);
+  /* XXX(palainp): Solo5 returns -1 and set errno on error, and it does not
+   * modify ptr, however both are not standardized. We can return NULL to the
+   * caller on error and do not check the returned value here. */
+  return ptr;
+}
diff --git a/nolibc/puts.c b/nolibc/puts.c
new file mode 100644
index 00000000..a8c366a0
--- /dev/null
+++ b/nolibc/puts.c
@@ -0,0 +1,17 @@
+#include <string.h>
+#include <unistd.h>
+
+extern void solo5_console_write(const char *, size_t);
+
+int puts(const char *s)
+{
+    size_t len = strlen(s);
+    solo5_console_write(s, len);
+    return (len);
+}
+
+int putchar(int chr)
+{
+    solo5_console_write((char *) &chr, 1);
+    return (1);
+}
diff --git a/nolibc/stubs.c b/nolibc/stubs.c
index 5f951b0a..155c0e6e 100644
--- a/nolibc/stubs.c
+++ b/nolibc/stubs.c
@@ -55,8 +55,11 @@ STUB_WARN_ONCE(int, getc, EOF);
 STUB_WARN_ONCE(int, ungetc, EOF);
 STUB_WARN_ONCE(int, fwrite, 0);
 STUB_WARN_ONCE(int, fputc, EOF);
+STUB_WARN_ONCE(int, fputs, EOF);
 STUB_WARN_ONCE(int, putc, EOF);
 STUB_WARN_ONCE(int, ferror, 1);
+STUB_WARN_ONCE(int, fopen, 1);
+STUB_WARN_ONCE(int, fclose, 1);
 
 /* stdlib.h */
 STUB_WARN_ONCE(char *, getenv, NULL);
@@ -75,6 +78,7 @@ STUB_ABORT(read);
 STUB_IGNORE(int, readlink, -1);
 STUB_ABORT(unlink);
 STUB_ABORT(rmdir);
+STUB_ABORT(ftruncate);
 
 /* dirent.h */
 STUB_WARN_ONCE(int, closedir, -1);
@@ -100,3 +104,49 @@ STUB_ABORT(strerror);
 /* sys/stat.h */
 STUB_WARN_ONCE(int, stat, -1);
 STUB_ABORT(mkdir);
+
+/* pthread.h */
+STUB_IGNORE(int, pthread_join, 0);
+STUB_IGNORE(int, pthread_create, 0);
+STUB_IGNORE(int, pthread_attr_init, 0);
+STUB_ABORT(pthread_cleanup_push);
+STUB_ABORT(pthread_cleanup_pop);
+
+STUB_IGNORE(int, munmap, 0); /* TODO: Implement munmap correctly and avoid memory leaks */
+
+int memory_order_release;
+int memory_order_acquire;
+int memory_order_relaxed;
+
+STUB_ABORT(atomic_store_explicit);
+STUB_ABORT(atomic_exchange);
+
+/* above that line, for OCaml 5, those are only required (i guess) for the configure step */
+STUB_IGNORE(int, pthread_mutex_lock, 0);
+STUB_IGNORE(int, pthread_mutex_trylock, 0);
+STUB_IGNORE(int, pthread_mutex_unlock, 0);
+STUB_IGNORE(int, pthread_mutex_destroy, 0);
+STUB_IGNORE(int, pthread_mutex_init, 0);
+
+STUB_IGNORE(int, pthread_mutexattr_init, 0);
+STUB_IGNORE(int, pthread_mutexattr_destroy, 0);
+STUB_IGNORE(int, pthread_mutexattr_settype, 0);
+
+STUB_IGNORE(int, pthread_sigmask, 0);
+
+STUB_IGNORE(int, pthread_equal, 1);
+
+STUB_IGNORE(int, pthread_condattr_init, 0);
+/* TODO: Is there a memory leak in OCaml? Shouldn't there be a call to pthread_condattr_destroy? */
+
+STUB_IGNORE(int, pthread_cond_init, 0);
+STUB_ABORT(pthread_cond_destroy);
+STUB_ABORT(pthread_cond_wait);
+STUB_ABORT(pthread_cond_signal);
+STUB_IGNORE(int, pthread_cond_broadcast, 0);
+STUB_ABORT(pthread_self);
+STUB_ABORT(pthread_detach);
+
+STUB_ABORT(sigfillset);
+STUB_ABORT(usleep);
+STUB_ABORT(strerror_r);
diff --git a/nolibc/sysconf.c b/nolibc/sysconf.c
new file mode 100644
index 00000000..81297ec9
--- /dev/null
+++ b/nolibc/sysconf.c
@@ -0,0 +1,11 @@
+#include <unistd.h>
+#include <sys/mman.h>
+
+long sysconf(int x) {
+  switch (x) {
+  case _SC_PAGESIZE: /* _SC_PAGE_SIZE */
+    return OCAML_SOLO5_PAGESIZE;
+  default:
+    return -1;
+  }
+}
diff --git a/nolibc/sysdeps_solo5.c b/nolibc/sysdeps_solo5.c
index dacd0215..b98c5875 100644
--- a/nolibc/sysdeps_solo5.c
+++ b/nolibc/sysdeps_solo5.c
@@ -76,6 +76,7 @@ static uintptr_t sbrk_start;
 static uintptr_t sbrk_end;
 static uintptr_t sbrk_cur;
 static uintptr_t sbrk_guard_size;
+static uintptr_t tls_main;
 
 /*
  * To be called by Mirage/Solo5 before calling caml_startup().
@@ -96,6 +97,20 @@ void _nolibc_init(uintptr_t heap_start, size_t heap_size)
 
     sbrk_start = sbrk_cur = heap_start;
     sbrk_end = heap_start + heap_size;
+
+    tls_main = (uintptr_t)calloc(solo5_tls_size(), sizeof(uint8_t));
+    if (tls_main == (uintptr_t)NULL) {
+        solo5_console_write("TLS alloc failed\n", 17);
+        abort();
+    }
+    if (solo5_tls_init(tls_main) != SOLO5_R_OK) {
+        solo5_console_write("TLS init failed\n", 16);
+        abort();
+    }
+    if (solo5_set_tls_base(solo5_tls_tp_offset(tls_main)) != SOLO5_R_OK) {
+        solo5_console_write("TLS set failed\n", 15);
+        abort();
+    }
 }
 
 /*
diff --git a/ocaml-solo5-cross-aarch64.opam b/ocaml-solo5-cross-aarch64.opam
index f58f85d2..c2b79aca 100644
--- a/ocaml-solo5-cross-aarch64.opam
+++ b/ocaml-solo5-cross-aarch64.opam
@@ -21,7 +21,7 @@ depends: [
   "conf-which" {build}
   "ocamlfind" {build} # needed by dune context (for tests)
   "ocaml-src" {build}
-  "ocaml" {>= "4.12.1" & < "4.15.0"}
+  "ocaml" {>= "5.0" & < "5.1"}
   "solo5" {>= "0.7.0"}
   "solo5-cross-aarch64" {>= "0.7.0" }
 ]
diff --git a/ocaml-solo5.opam b/ocaml-solo5.opam
index 3df9e566..c0b3d7ff 100644
--- a/ocaml-solo5.opam
+++ b/ocaml-solo5.opam
@@ -22,7 +22,7 @@ depends: [
   "conf-which" {build}
   "ocamlfind" {build} # needed by dune context (for tests)
   "ocaml-src" {build}
-  "ocaml" {>= "4.12.1" & < "4.15.0"}
+  "ocaml" {>= "5.0" & < "5.1"}
   "solo5" {>= "0.7.0"}
 ]
 conflicts: [
diff --git a/test/startup.c b/test/startup.c
index 5544c44d..8d9d5b04 100644
--- a/test/startup.c
+++ b/test/startup.c
@@ -13,4 +13,5 @@ void _nolibc_init(uintptr_t heap_start, size_t heap_size); // defined in nolibc/
 int solo5_app_main(const struct solo5_start_info *si) {
     _nolibc_init(si->heap_start, si->heap_size);
     caml_startup(unused_argv);
+    return 0;
 }