diff --git a/src/journal/journal-file.c b/src/journal/journal-file.c
index 4ff38de2e6..84e64aef6c 100644
--- a/src/journal/journal-file.c
+++ b/src/journal/journal-file.c
@@ -727,7 +727,7 @@ static unsigned type_to_context(ObjectType type) {
         return type > OBJECT_UNUSED && type < _OBJECT_TYPE_MAX ? type : 0;
 }
 
-static int journal_file_move_to(JournalFile *f, ObjectType type, bool keep_always, uint64_t offset, uint64_t size, void **ret) {
+static int journal_file_move_to(JournalFile *f, ObjectType type, bool keep_always, uint64_t offset, uint64_t size, void **ret, size_t *ret_size) {
         int r;
 
         assert(f);
@@ -749,7 +749,7 @@ static int journal_file_move_to(JournalFile *f, ObjectType type, bool keep_alway
                         return -EADDRNOTAVAIL;
         }
 
-        return mmap_cache_get(f->mmap, f->cache_fd, f->prot, type_to_context(type), keep_always, offset, size, &f->last_stat, ret);
+        return mmap_cache_get(f->mmap, f->cache_fd, f->prot, type_to_context(type), keep_always, offset, size, &f->last_stat, ret, ret_size);
 }
 
 static uint64_t minimum_header_size(Object *o) {
@@ -773,6 +773,7 @@ static uint64_t minimum_header_size(Object *o) {
 int journal_file_move_to_object(JournalFile *f, ObjectType type, uint64_t offset, Object **ret) {
         int r;
         void *t;
+        size_t tsize;
         Object *o;
         uint64_t s;
 
@@ -791,7 +792,7 @@ int journal_file_move_to_object(JournalFile *f, ObjectType type, uint64_t offset
                 return -EBADMSG;
         }
 
-        r = journal_file_move_to(f, type, false, offset, sizeof(ObjectHeader), &t);
+        r = journal_file_move_to(f, type, false, offset, sizeof(ObjectHeader), &t, &tsize);
         if (r < 0)
                 return r;
 
@@ -822,8 +823,8 @@ int journal_file_move_to_object(JournalFile *f, ObjectType type, uint64_t offset
                 return -EBADMSG;
         }
 
-        if (s > sizeof(ObjectHeader)) {
-                r = journal_file_move_to(f, type, false, offset, s, &t);
+        if (s > tsize) {
+                r = journal_file_move_to(f, type, false, offset, s, &t, NULL);
                 if (r < 0)
                         return r;
 
@@ -893,7 +894,7 @@ int journal_file_append_object(JournalFile *f, ObjectType type, uint64_t size, O
         if (r < 0)
                 return r;
 
-        r = journal_file_move_to(f, type, false, p, size, &t);
+        r = journal_file_move_to(f, type, false, p, size, &t, NULL);
         if (r < 0)
                 return r;
 
@@ -991,7 +992,7 @@ int journal_file_map_data_hash_table(JournalFile *f) {
                                  OBJECT_DATA_HASH_TABLE,
                                  true,
                                  p, s,
-                                 &t);
+                                 &t, NULL);
         if (r < 0)
                 return r;
 
@@ -1017,7 +1018,7 @@ int journal_file_map_field_hash_table(JournalFile *f) {
                                  OBJECT_FIELD_HASH_TABLE,
                                  true,
                                  p, s,
-                                 &t);
+                                 &t, NULL);
         if (r < 0)
                 return r;
 
@@ -3196,7 +3197,7 @@ int journal_file_open(
                 goto fail;
         }
 
-        r = mmap_cache_get(f->mmap, f->cache_fd, f->prot, CONTEXT_HEADER, true, 0, PAGE_ALIGN(sizeof(Header)), &f->last_stat, &h);
+        r = mmap_cache_get(f->mmap, f->cache_fd, f->prot, CONTEXT_HEADER, true, 0, PAGE_ALIGN(sizeof(Header)), &f->last_stat, &h, NULL);
         if (r < 0)
                 goto fail;
 
diff --git a/src/journal/journal-verify.c b/src/journal/journal-verify.c
index 9feb5b5ae6..3f4c38ccde 100644
--- a/src/journal/journal-verify.c
+++ b/src/journal/journal-verify.c
@@ -392,7 +392,7 @@ static int contains_uint64(MMapCache *m, MMapFileDescriptor *f, uint64_t n, uint
 
                 c = (a + b) / 2;
 
-                r = mmap_cache_get(m, f, PROT_READ|PROT_WRITE, 0, false, c * sizeof(uint64_t), sizeof(uint64_t), NULL, (void **) &z);
+                r = mmap_cache_get(m, f, PROT_READ|PROT_WRITE, 0, false, c * sizeof(uint64_t), sizeof(uint64_t), NULL, (void **) &z, NULL);
                 if (r < 0)
                         return r;
 
diff --git a/src/journal/mmap-cache.c b/src/journal/mmap-cache.c
index 3e076f8fea..6e60d24dcf 100644
--- a/src/journal/mmap-cache.c
+++ b/src/journal/mmap-cache.c
@@ -345,7 +345,8 @@ static int try_context(
                 bool keep_always,
                 uint64_t offset,
                 size_t size,
-                void **ret) {
+                void **ret,
+                size_t *ret_size) {
 
         Context *c;
 
@@ -377,6 +378,9 @@ static int try_context(
         c->window->keep_always = c->window->keep_always || keep_always;
 
         *ret = (uint8_t*) c->window->ptr + (offset - c->window->offset);
+        if (ret_size)
+                *ret_size = c->window->size - (offset - c->window->offset);
+
         return 1;
 }
 
@@ -388,7 +392,8 @@ static int find_mmap(
                 bool keep_always,
                 uint64_t offset,
                 size_t size,
-                void **ret) {
+                void **ret,
+                size_t *ret_size) {
 
         Window *w;
         Context *c;
@@ -416,6 +421,9 @@ static int find_mmap(
         w->keep_always = w->keep_always || keep_always;
 
         *ret = (uint8_t*) w->ptr + (offset - w->offset);
+        if (ret_size)
+                *ret_size = w->size - (offset - w->offset);
+
         return 1;
 }
 
@@ -455,7 +463,8 @@ static int add_mmap(
                 uint64_t offset,
                 size_t size,
                 struct stat *st,
-                void **ret) {
+                void **ret,
+                size_t *ret_size) {
 
         uint64_t woffset, wsize;
         Context *c;
@@ -513,6 +522,9 @@ static int add_mmap(
         context_attach_window(c, w);
 
         *ret = (uint8_t*) w->ptr + (offset - w->offset);
+        if (ret_size)
+                *ret_size = w->size - (offset - w->offset);
+
         return 1;
 
 outofmem:
@@ -529,7 +541,8 @@ int mmap_cache_get(
                 uint64_t offset,
                 size_t size,
                 struct stat *st,
-                void **ret) {
+                void **ret,
+                size_t *ret_size) {
 
         int r;
 
@@ -541,14 +554,14 @@ int mmap_cache_get(
         assert(context < MMAP_CACHE_MAX_CONTEXTS);
 
         /* Check whether the current context is the right one already */
-        r = try_context(m, f, prot, context, keep_always, offset, size, ret);
+        r = try_context(m, f, prot, context, keep_always, offset, size, ret, ret_size);
         if (r != 0) {
                 m->n_hit++;
                 return r;
         }
 
         /* Search for a matching mmap */
-        r = find_mmap(m, f, prot, context, keep_always, offset, size, ret);
+        r = find_mmap(m, f, prot, context, keep_always, offset, size, ret, ret_size);
         if (r != 0) {
                 m->n_hit++;
                 return r;
@@ -557,7 +570,7 @@ int mmap_cache_get(
         m->n_missed++;
 
         /* Create a new mmap */
-        return add_mmap(m, f, prot, context, keep_always, offset, size, st, ret);
+        return add_mmap(m, f, prot, context, keep_always, offset, size, st, ret, ret_size);
 }
 
 unsigned mmap_cache_get_hit(MMapCache *m) {
diff --git a/src/journal/mmap-cache.h b/src/journal/mmap-cache.h
index 7b33218563..cf6af1906a 100644
--- a/src/journal/mmap-cache.h
+++ b/src/journal/mmap-cache.h
@@ -41,7 +41,8 @@ int mmap_cache_get(
         uint64_t offset,
         size_t size,
         struct stat *st,
-        void **ret);
+        void **ret,
+        size_t *ret_size);
 MMapFileDescriptor * mmap_cache_add_fd(MMapCache *m, int fd);
 void mmap_cache_free_fd(MMapCache *m, MMapFileDescriptor *f);
 
diff --git a/src/journal/test-mmap-cache.c b/src/journal/test-mmap-cache.c
index c51b069f8b..702434efd2 100644
--- a/src/journal/test-mmap-cache.c
+++ b/src/journal/test-mmap-cache.c
@@ -51,23 +51,23 @@ int main(int argc, char *argv[]) {
         assert_se(z >= 0);
         unlink(pz);
 
-        r = mmap_cache_get(m, fx, PROT_READ, 0, false, 1, 2, NULL, &p);
+        r = mmap_cache_get(m, fx, PROT_READ, 0, false, 1, 2, NULL, &p, NULL);
         assert_se(r >= 0);
 
-        r = mmap_cache_get(m, fx, PROT_READ, 0, false, 2, 2, NULL, &q);
+        r = mmap_cache_get(m, fx, PROT_READ, 0, false, 2, 2, NULL, &q, NULL);
         assert_se(r >= 0);
 
         assert_se((uint8_t*) p + 1 == (uint8_t*) q);
 
-        r = mmap_cache_get(m, fx, PROT_READ, 1, false, 3, 2, NULL, &q);
+        r = mmap_cache_get(m, fx, PROT_READ, 1, false, 3, 2, NULL, &q, NULL);
         assert_se(r >= 0);
 
         assert_se((uint8_t*) p + 2 == (uint8_t*) q);
 
-        r = mmap_cache_get(m, fx, PROT_READ, 0, false, 16ULL*1024ULL*1024ULL, 2, NULL, &p);
+        r = mmap_cache_get(m, fx, PROT_READ, 0, false, 16ULL*1024ULL*1024ULL, 2, NULL, &p, NULL);
         assert_se(r >= 0);
 
-        r = mmap_cache_get(m, fx, PROT_READ, 1, false, 16ULL*1024ULL*1024ULL+1, 2, NULL, &q);
+        r = mmap_cache_get(m, fx, PROT_READ, 1, false, 16ULL*1024ULL*1024ULL+1, 2, NULL, &q, NULL);
         assert_se(r >= 0);
 
         assert_se((uint8_t*) p + 1 == (uint8_t*) q);