diff --git a/inflate.c b/inflate.c
index 4feac091..474e3712 100644
--- a/inflate.c
+++ b/inflate.c
@@ -232,7 +232,7 @@ int ZEXPORT inflatePrime(z_streamp strm, int bits, int value) {
         state->bits = 0;
         return Z_OK;
     }
-    if (bits > 16 || state->bits + (uInt)bits > 32) return Z_STREAM_ERROR;
+    if (bits > 16 || state->bits + (uInt)bits >= 32) return Z_STREAM_ERROR;
     value &= (1L << bits) - 1;
     state->hold += (unsigned)value << state->bits;
     state->bits += (uInt)bits;