diff --git a/test/wal_off/oom.result b/test/wal_off/oom.result
index c629d4662349dc51444cbac6de7bf947fcb6f021..fa357432069c848967894e6ab0bef8d39c5986a9 100644
--- a/test/wal_off/oom.result
+++ b/test/wal_off/oom.result
@@ -218,6 +218,10 @@ space = box.schema.space.create('tweedledum')
 index = space:create_index('primary', { type = 'hash' })
 ---
 ...
+collectgarbage('collect')
+---
+- 0
+...
 for i=1,10000 do space:insert{i, str} end
 ---
 - error: Failed to allocate 15019 bytes in slab allocator for tuple
@@ -239,6 +243,10 @@ index:count()
 ---
 - 0
 ...
+collectgarbage('collect')
+---
+- 0
+...
 for i=1,10000 do space:insert{i, str} end
 ---
 - error: Failed to allocate 15019 bytes in slab allocator for tuple
diff --git a/test/wal_off/oom.test.lua b/test/wal_off/oom.test.lua
index 2ebdf96f816cec4bb81136a522dbeaad4901ee6e..88a1f0fb4e32622ca5c9323ce89c44877df06488 100644
--- a/test/wal_off/oom.test.lua
+++ b/test/wal_off/oom.test.lua
@@ -85,6 +85,7 @@ str = string.rep('a', 15000) -- about size of index memory block
 space = box.schema.space.create('tweedledum')
 index = space:create_index('primary', { type = 'hash' })
 
+collectgarbage('collect')
 for i=1,10000 do space:insert{i, str} end
 definatelly_used = index:count() * 16 * 1024
 2 * definatelly_used > arena_bytes -- at least half memory used
@@ -92,6 +93,7 @@ to_del = index:count()
 for i=1,to_del do space:delete{i} end
 index:count()
 
+collectgarbage('collect')
 for i=1,10000 do space:insert{i, str} end
 definatelly_used = index:count() * 16 * 1024
 2 * definatelly_used > arena_bytes -- at least half memory used