diff --git a/tests/decodecorpus.c b/tests/decodecorpus.c
index dfda93923..3e20b3ba5 100644
--- a/tests/decodecorpus.c
+++ b/tests/decodecorpus.c
@@ -683,8 +683,8 @@ static U32 generateSequences(U32* seed, frame_t* frame, seqStore_t* seqStore,
                          1;
                 if (info.useDict && (RAND(seed) & 1)) {
                     /* need to occasionally generate offsets that go past the start */
-                    U32 const lenPastStart = RAND(seed) % info.dictContentSize;
-                    offset = offset+lenPastStart;
+                    U32 const lenPastStart = RAND(seed) % info.dictContentSize + 1;
+                    offset = ((BYTE*)srcPtr - (BYTE*)frame->srcStart)+lenPastStart;
                 }
                 offsetCode = offset + ZSTD_REP_MOVE;
                 repIndex = 2;