diff --git a/lib/compress/zstd_opt.c b/lib/compress/zstd_opt.c
index 562a6b17bc9..96be6cf8db4 100644
--- a/lib/compress/zstd_opt.c
+++ b/lib/compress/zstd_opt.c
@@ -155,7 +155,14 @@ ZSTD_rescaleFreqs(optState_t* const optPtr,
         }
 
         assert(optPtr->symbolCosts != NULL);
-        if (optPtr->symbolCosts->huf.repeatMode == HUF_repeat_valid) {
+        /* The dictionary's FSE tables are only complete when every repeat
+         * mode is valid.  A table with missing symbols returns a fake cost
+         * of tableLog + 1 from FSE_getMaxNbBits(), which is not a valid input
+         * to the scaled frequency calculation below. */
+        if (optPtr->symbolCosts->huf.repeatMode == HUF_repeat_valid &&
+            optPtr->symbolCosts->fse.litlength_repeatMode == FSE_repeat_valid &&
+            optPtr->symbolCosts->fse.matchlength_repeatMode == FSE_repeat_valid &&
+            optPtr->symbolCosts->fse.offcode_repeatMode == FSE_repeat_valid) {
 
             /* huffman stats covering the full value set : table presumed generated by dictionary */
             optPtr->priceType = zop_dynamic;