diff --git a/src/etcp.c b/src/etcp.c
index 15ec8894..92c0a47a 100644
--- a/src/etcp.c
+++ b/src/etcp.c
@@ -70,7 +70,7 @@ static int inflight_seq_cmp(const void* a, const void* b) {
 
 static void feed_dgram_to_asm(struct ETCP_CONN* etcp, struct PKTNORM* pn,
                                uint8_t* dgram, uint16_t dgram_len,
-                               uint8_t** asm_buf, uint16_t* asm_len, uint16_t* asm_cap,
+                               uint8_t** asm_buf, uint16_t* asm_len, uint32_t* asm_cap,
                                uint32_t* returned) {
     uint32_t need = (uint32_t)*asm_len + dgram_len;
     if (need >= ASM_BUF_MAX_SIZE) {
@@ -78,9 +78,10 @@ static void feed_dgram_to_asm(struct ETCP_CONN* etcp, struct PKTNORM* pn,
         return;
     }
     if (need > *asm_cap) {
-        uint16_t new_cap = *asm_cap ? *asm_cap : 256;
+        uint32_t new_cap = *asm_cap ? *asm_cap : 256;
         while (new_cap < need) new_cap *= 2;
-        uint8_t* new_buf = u_realloc(*asm_buf, new_cap);
+        if (new_cap > 0xFFFF) new_cap = 0xFFFF;
+        uint8_t* new_buf = u_realloc(*asm_buf, (uint16_t)new_cap);
         if (!new_buf) return;
         *asm_buf = new_buf;
         *asm_cap = new_cap;
@@ -138,7 +139,7 @@ static void etcp_return_inflight_to_normalizer(struct ETCP_CONN* etcp) {
 
     uint8_t* asm_buf = NULL;
     uint16_t asm_len = 0;
-    uint16_t asm_cap = 0;
+    uint32_t asm_cap = 0;
     uint32_t returned_packets = 0;
 
     for (int i = 0; i < inflight_count; i++) {