diff --git a/include/haproxy/shctx-t.h b/include/haproxy/shctx-t.h
index 20d288769..533536be8 100644
--- a/include/haproxy/shctx-t.h
+++ b/include/haproxy/shctx-t.h
@@ -17,7 +17,8 @@
 #if !defined (USE_PRIVATE_CACHE) && defined(USE_PTHREAD_PSHARED)
 #include <pthread.h>
 #endif
-#include <haproxy/list.h>
+#include <haproxy/api-t.h>
+#include <haproxy/thread-t.h>
 
 #ifndef SHSESS_BLOCK_MIN_SIZE
 #define SHSESS_BLOCK_MIN_SIZE 128
@@ -54,6 +55,8 @@ struct shared_context {
 #else
 	unsigned int waiters;
 #endif
+#else
+	__decl_thread(HA_SPINLOCK_T lock);  // used when USE_PRIVATE_CACHE=1
 #endif
 	struct list avail;  /* list for active and free blocks */
 	struct list hot;     /* list for locked blocks */
diff --git a/include/haproxy/shctx.h b/include/haproxy/shctx.h
index 050dbc3ab..4f8c23f7f 100644
--- a/include/haproxy/shctx.h
+++ b/include/haproxy/shctx.h
@@ -14,7 +14,7 @@
 #ifndef __HAPROXY_SHCTX_H
 #define __HAPROXY_SHCTX_H
 
-#include <haproxy/api-t.h>
+#include <haproxy/api.h>
 #include <haproxy/list.h>
 #include <haproxy/shctx-t.h>
 
@@ -28,6 +28,8 @@
 #include <sys/syscall.h>
 #endif
 #endif
+#else
+#include <haproxy/thread.h>
 #endif
 
 int shctx_init(struct shared_context **orig_shctx,
@@ -47,9 +49,10 @@ int shctx_row_data_get(struct shared_context *shctx, struct shared_block *first,
 /* Lock functions */
 
 #if defined (USE_PRIVATE_CACHE)
+extern int use_shared_mem;
 
-#define shctx_lock(shctx)
-#define shctx_unlock(shctx)
+#define shctx_lock(shctx)   if (use_shared_mem) HA_SPIN_LOCK(SHCTX_LOCK, &shctx->lock)
+#define shctx_unlock(shctx) if (use_shared_mem) HA_SPIN_UNLOCK(SHCTX_LOCK, &shctx->lock)
 
 #elif defined (USE_PTHREAD_PSHARED)
 extern int use_shared_mem;
diff --git a/include/haproxy/thread.h b/include/haproxy/thread.h
index b1fed39b4..b64e2bb24 100644
--- a/include/haproxy/thread.h
+++ b/include/haproxy/thread.h
@@ -380,6 +380,7 @@ enum lock_label {
 	STK_SESS_LOCK,
 	APPLETS_LOCK,
 	PEER_LOCK,
+	SHCTX_LOCK,
 	SSL_LOCK,
 	SSL_GEN_CERTS_LOCK,
 	PATREF_LOCK,
@@ -431,6 +432,7 @@ static inline const char *lock_label(enum lock_label label)
 	case STK_SESS_LOCK:        return "STK_SESS";
 	case APPLETS_LOCK:         return "APPLETS";
 	case PEER_LOCK:            return "PEER";
+	case SHCTX_LOCK:           return "SHCTX";
 	case SSL_LOCK:             return "SSL";
 	case SSL_GEN_CERTS_LOCK:   return "SSL_GEN_CERTS";
 	case PATREF_LOCK:          return "PATREF";
diff --git a/src/shctx.c b/src/shctx.c
index 1160a1b25..0ac3d5e83 100644
--- a/src/shctx.c
+++ b/src/shctx.c
@@ -17,12 +17,8 @@
 #include <haproxy/list.h>
 #include <haproxy/shctx.h>
 
-#if !defined (USE_PRIVATE_CACHE)
-
 int use_shared_mem = 0;
 
-#endif
-
 /*
  * Reserve a new row if <first> is null, put it in the hotlist, set the refcount to 1
  * or append new blocks to the row with <first> as first block if non null.
@@ -296,10 +292,8 @@ int shctx_init(struct shared_context **orig_shctx, int maxblocks, int blocksize,
 	int i;
 	struct shared_context *shctx;
 	int ret;
-#ifndef USE_PRIVATE_CACHE
 #ifdef USE_PTHREAD_PSHARED
 	pthread_mutexattr_t attr;
-#endif
 #endif
 	void *cur;
 	int maptype = MAP_PRIVATE;
@@ -311,10 +305,8 @@ int shctx_init(struct shared_context **orig_shctx, int maxblocks, int blocksize,
 	blocksize = (blocksize + sizeof(void *) - 1) & -sizeof(void *);
 	extra     = (extra     + sizeof(void *) - 1) & -sizeof(void *);
 
-#ifndef USE_PRIVATE_CACHE
 	if (shared)
 		maptype = MAP_SHARED;
-#endif
 
 	shctx = (struct shared_context *)mmap(NULL, sizeof(struct shared_context) + extra + (maxblocks * (sizeof(struct shared_block) + blocksize)),
 	                                      PROT_READ | PROT_WRITE, maptype | MAP_ANON, -1, 0);
@@ -326,8 +318,8 @@ int shctx_init(struct shared_context **orig_shctx, int maxblocks, int blocksize,
 
 	shctx->nbav = 0;
 
-#ifndef USE_PRIVATE_CACHE
 	if (maptype == MAP_SHARED) {
+#ifndef USE_PRIVATE_CACHE
 #ifdef USE_PTHREAD_PSHARED
 		if (pthread_mutexattr_init(&attr)) {
 			munmap(shctx, sizeof(struct shared_context) + extra + (maxblocks * (sizeof(struct shared_block) + blocksize)));
@@ -353,10 +345,12 @@ int shctx_init(struct shared_context **orig_shctx, int maxblocks, int blocksize,
 		}
 #else
 		shctx->waiters = 0;
+#endif
+#else
+		HA_SPIN_INIT(&shctx->lock);
 #endif
 		use_shared_mem = 1;
 	}
-#endif
 
 	LIST_INIT(&shctx->avail);
 	LIST_INIT(&shctx->hot);