diff --git a/src/util-decode-mime.c b/src/util-decode-mime.c
index f58a701b01..4b9cd23f34 100644
--- a/src/util-decode-mime.c
+++ b/src/util-decode-mime.c
@@ -1176,13 +1176,6 @@ static uint32_t ProcessBase64Remainder(
 
     SCLogDebug("len %u force %d", len, force);
 
-    /* should be impossible, but lets be defensive */
-    DEBUG_VALIDATE_BUG_ON(state->bvr_len > B64_BLOCK);
-    if (state->bvr_len > B64_BLOCK) {
-        state->bvr_len = 0;
-        return 0;
-    }
-
     /* Strip spaces in remainder */
     for (uint8_t i = 0; i < state->bvr_len; i++) {
         if (IsBase64Alphabet(state->bvremain[i])) {
@@ -1193,6 +1186,13 @@ static uint32_t ProcessBase64Remainder(
         }
     }
 
+    /* should be impossible, but lets be defensive */
+    DEBUG_VALIDATE_BUG_ON(cnt > B64_BLOCK);
+    if (cnt > B64_BLOCK) {
+        state->bvr_len = 0;
+        return 0;
+    }
+
     /* if we don't have 4 bytes see if we can fill it from `buf` */
     if (buf && len > 0 && cnt != B64_BLOCK) {
         for (uint32_t i = 0; i < len && cnt < B64_BLOCK; i++) {