diff --git a/include/mbedtls/ssl_cache.h b/include/mbedtls/ssl_cache.h
index 41ada540bc..55dcf77c3b 100644
--- a/include/mbedtls/ssl_cache.h
+++ b/include/mbedtls/ssl_cache.h
@@ -134,7 +134,7 @@ int mbedtls_ssl_cache_set(void *data,
  *
  * \return                0: The cache entry for session with provided ID
  *                           is removed or does not exist.
- *                        1: Internal error.
+ *                        Otherwise: fail.
  */
 int mbedtls_ssl_cache_remove(void *data,
                              unsigned char const *session_id,
diff --git a/library/ssl_cache.c b/library/ssl_cache.c
index d93508c6b3..048c21d4f0 100644
--- a/library/ssl_cache.c
+++ b/library/ssl_cache.c
@@ -92,8 +92,8 @@ int mbedtls_ssl_cache_get(void *data,
     mbedtls_ssl_cache_entry *entry;
 
 #if defined(MBEDTLS_THREADING_C)
-    if (mbedtls_mutex_lock(&cache->mutex) != 0) {
-        return 1;
+    if ((ret = mbedtls_mutex_lock(&cache->mutex)) != 0) {
+        return ret;
     }
 #endif
 
@@ -114,7 +114,7 @@ int mbedtls_ssl_cache_get(void *data,
 exit:
 #if defined(MBEDTLS_THREADING_C)
     if (mbedtls_mutex_unlock(&cache->mutex) != 0) {
-        ret = 1;
+        ret = MBEDTLS_ERR_THREADING_MUTEX_ERROR;
     }
 #endif
 
@@ -318,7 +318,7 @@ int mbedtls_ssl_cache_set(void *data,
 exit:
 #if defined(MBEDTLS_THREADING_C)
     if (mbedtls_mutex_unlock(&cache->mutex) != 0) {
-        ret = 1;
+        ret = MBEDTLS_ERR_THREADING_MUTEX_ERROR;
     }
 #endif
 
@@ -341,8 +341,8 @@ int mbedtls_ssl_cache_remove(void *data,
     mbedtls_ssl_cache_entry *prev;
 
 #if defined(MBEDTLS_THREADING_C)
-    if (mbedtls_mutex_lock(&cache->mutex) != 0) {
-        return 1;
+    if ((ret = mbedtls_mutex_lock(&cache->mutex)) != 0) {
+        return ret;
     }
 #endif
 
@@ -373,7 +373,7 @@ free:
 exit:
 #if defined(MBEDTLS_THREADING_C)
     if (mbedtls_mutex_unlock(&cache->mutex) != 0) {
-        ret = 1;
+        ret = MBEDTLS_ERR_THREADING_MUTEX_ERROR;
     }
 #endif