diff --git a/nimsuggest/tester.nim b/nimsuggest/tester.nim
index b69569288d..46471b756c 100644
--- a/nimsuggest/tester.nim
+++ b/nimsuggest/tester.nim
@@ -74,6 +74,18 @@ proc parseTest(filename: string; epcMode=false): Test =
         # else: ignore empty lines for better readability of the specs
     inc i
   tmp.close()
+  # Give every run a private, freshly-wiped NIF cache. Under IC nimsuggest reuses
+  # the on-disk NIFs of a previous session, but per-symbol usage counts are not
+  # serialized, so a warm start ranks `sug`/`con` results differently than a cold
+  # one (e.g. `string` outranks `int` because `system` was loaded, not re-walked).
+  # The tester runs the stdio and EPC variants of a test as two processes sharing
+  # the same temp project name — without isolation the second inherits the first's
+  # NIFs and the result order flips. A dedicated, cleared cache keeps both cold and
+  # deterministic.
+  let nimcache = getTempDir() / ("nimsuggest_cache_" &
+    extractFilename(result.dest).changeFileExt("") & (if epcMode: "_epc" else: "_stdin"))
+  removeDir(nimcache)
+  result.cmd.add " --nimcache:" & nimcache
   # now that we know the markers, substitute them:
   for a in mitems(result.script):
     a[0] = a[0] % markers