diff --git a/src/native/external/zlib-ng/arch/generic/crc32_braid_c.c b/src/native/external/zlib-ng/arch/generic/crc32_braid_c.c
index 7d8028f6d70555..f80071042d77c6 100644
--- a/src/native/external/zlib-ng/arch/generic/crc32_braid_c.c
+++ b/src/native/external/zlib-ng/arch/generic/crc32_braid_c.c
@@ -192,7 +192,8 @@ Z_INTERNAL uint32_t PREFIX(crc32_braid)(uint32_t crc, const uint8_t *buf, size_t
 #endif
 #endif
         words += N;
-        c = ZSWAPWORD(comb);
+        Assert(comb <= UINT32_MAX, "comb should fit in uint32_t");
+        c = (uint32_t)ZSWAPWORD(comb);
 
         /* Update the pointer to the remaining bytes to process. */
         buf = (const unsigned char *)words;
diff --git a/src/native/external/zlib-ng/deflate.c b/src/native/external/zlib-ng/deflate.c
index 66b5506a521e5c..eb5ae0aabd5973 100644
--- a/src/native/external/zlib-ng/deflate.c
+++ b/src/native/external/zlib-ng/deflate.c
@@ -204,7 +204,7 @@ Z_INTERNAL deflate_allocs* alloc_deflate(PREFIX3(stream) *strm, int windowBits,
 
     /* Define sizes */
     int window_size = DEFLATE_ADJUST_WINDOW_SIZE((1 << windowBits) * 2);
-    int prev_size = (1 << windowBits) * sizeof(Pos);
+    int prev_size = (1 << windowBits) * (int)sizeof(Pos);
     int head_size = HASH_SIZE * sizeof(Pos);
     int pending_size = lit_bufsize * LIT_BUFS;
     int state_size = sizeof(deflate_state);
diff --git a/src/native/external/zlib-ng/deflate_p.h b/src/native/external/zlib-ng/deflate_p.h
index 7c74ebf5ad771a..abcc8b1c7c1255 100644
--- a/src/native/external/zlib-ng/deflate_p.h
+++ b/src/native/external/zlib-ng/deflate_p.h
@@ -78,8 +78,10 @@ static inline int zng_tr_tally_dist(deflate_state* s, uint32_t dist, uint32_t le
     /* dist: distance of matched string */
     /* len: match length-STD_MIN_MATCH */
 #ifdef LIT_MEM
-    s->d_buf[s->sym_next] = dist;
-    s->l_buf[s->sym_next++] = len;
+    Assert(dist <= UINT16_MAX, "dist should fit in uint16_t");
+    Assert(len <= UINT8_MAX, "len should fit in uint8_t");
+    s->d_buf[s->sym_next] = (uint16_t)dist;
+    s->l_buf[s->sym_next++] = (uint8_t)len;
 #else
     s->sym_buf[s->sym_next++] = (uint8_t)(dist);
     s->sym_buf[s->sym_next++] = (uint8_t)(dist >> 8);
diff --git a/src/native/external/zlib-ng/deflate_rle.c b/src/native/external/zlib-ng/deflate_rle.c
index 042800058f1ae5..fb17a63c5eb262 100644
--- a/src/native/external/zlib-ng/deflate_rle.c
+++ b/src/native/external/zlib-ng/deflate_rle.c
@@ -60,7 +60,7 @@ Z_INTERNAL block_state deflate_rle(deflate_state *s, int flush) {
         if (match_len >= STD_MIN_MATCH) {
             Assert(s->strstart <= UINT16_MAX, "strstart should fit in uint16_t");
             Assert(s->match_start <= UINT16_MAX, "match_start should fit in uint16_t");
-            check_match(s, (Pos)s->strstart, (Pos)s->strstart - 1, match_len);
+            check_match(s, (Pos)s->strstart, (Pos)(s->strstart - 1), match_len);
 
             bflush = zng_tr_tally_dist(s, 1, match_len - STD_MIN_MATCH);