diff --git a/design/mvp/CanonicalABI.md b/design/mvp/CanonicalABI.md
index 92e01e7f..360af744 100644
--- a/design/mvp/CanonicalABI.md
+++ b/design/mvp/CanonicalABI.md
@@ -1070,6 +1070,8 @@ host:
     self.inst.store.invoke(realloc, on_start, on_resolve)
     self.inst.may_leave = True
     assert(ptr is not None)
+    trap_if(ptr != align_to(ptr, alignment))
+    trap_if(ptr + new_byte_length > len(self.opts.memory))
     return ptr
 
   def allocate(self, alignment, byte_length):
@@ -2619,8 +2621,6 @@ def store_string_copy(cx, src, src_code_units, dst_code_unit_size, dst_alignment
   dst_byte_length = dst_code_unit_size * src_code_units
   assert(dst_byte_length <= REALLOC_I32_MAX)
   ptr = cx.allocate(dst_alignment, dst_byte_length)
-  trap_if(ptr != align_to(ptr, dst_alignment))
-  trap_if(ptr + dst_byte_length > len(cx.opts.memory))
   encoded = src.encode(dst_encoding)
   assert(dst_byte_length == len(encoded))
   cx.opts.memory[ptr : ptr+len(encoded)] = encoded
@@ -2642,19 +2642,16 @@ def store_latin1_to_utf8(cx, src, src_code_units):
 def store_string_to_utf8(cx, src, src_code_units, worst_case_size):
   assert(src_code_units <= REALLOC_I32_MAX)
   ptr = cx.allocate(1, src_code_units)
-  trap_if(ptr + src_code_units > len(cx.opts.memory))
   for i,code_point in enumerate(src):
     if ord(code_point) < 2**7:
       cx.opts.memory[ptr + i] = ord(code_point)
     else:
       assert(worst_case_size <= REALLOC_I32_MAX)
       ptr = cx.reallocate(ptr, src_code_units, 1, worst_case_size)
-      trap_if(ptr + worst_case_size > len(cx.opts.memory))
       encoded = src.encode('utf-8')
       cx.opts.memory[ptr+i : ptr+len(encoded)] = encoded[i : ]
       if worst_case_size > len(encoded):
         ptr = cx.reallocate(ptr, worst_case_size, 1, len(encoded))
-        trap_if(ptr + len(encoded) > len(cx.opts.memory))
       return (ptr, len(encoded))
   return (ptr, src_code_units)
 ```
@@ -2668,14 +2665,10 @@ def store_utf8_to_utf16(cx, src, src_code_units):
   worst_case_size = 2 * src_code_units
   assert(worst_case_size <= REALLOC_I32_MAX)
   ptr = cx.allocate(2, worst_case_size)
-  trap_if(ptr != align_to(ptr, 2))
-  trap_if(ptr + worst_case_size > len(cx.opts.memory))
   encoded = src.encode('utf-16-le')
   cx.opts.memory[ptr : ptr+len(encoded)] = encoded
   if len(encoded) < worst_case_size:
     ptr = cx.reallocate(ptr, worst_case_size, 2, len(encoded))
-    trap_if(ptr != align_to(ptr, 2))
-    trap_if(ptr + len(encoded) > len(cx.opts.memory))
   code_units = int(len(encoded) / 2)
   return (ptr, code_units)
 ```
@@ -2692,8 +2685,6 @@ bytes):
 def store_string_to_latin1_or_utf16(cx, src, src_code_units):
   assert(src_code_units <= REALLOC_I32_MAX)
   ptr = cx.allocate(2, src_code_units)
-  trap_if(ptr != align_to(ptr, 2))
-  trap_if(ptr + src_code_units > len(cx.opts.memory))
   dst_byte_length = 0
   for usv in src:
     if ord(usv) < (1 << 8):
@@ -2703,8 +2694,6 @@ def store_string_to_latin1_or_utf16(cx, src, src_code_units):
       worst_case_size = 2 * src_code_units
       assert(worst_case_size <= REALLOC_I32_MAX)
       ptr = cx.reallocate(ptr, src_code_units, 2, worst_case_size)
-      trap_if(ptr != align_to(ptr, 2))
-      trap_if(ptr + worst_case_size > len(cx.opts.memory))
       for j in range(dst_byte_length-1, -1, -1):
         cx.opts.memory[ptr + 2*j] = cx.opts.memory[ptr + j]
         cx.opts.memory[ptr + 2*j + 1] = 0
@@ -2712,14 +2701,10 @@ def store_string_to_latin1_or_utf16(cx, src, src_code_units):
       cx.opts.memory[ptr+2*dst_byte_length : ptr+len(encoded)] = encoded[2*dst_byte_length : ]
       if worst_case_size > len(encoded):
         ptr = cx.reallocate(ptr, worst_case_size, 2, len(encoded))
-        trap_if(ptr != align_to(ptr, 2))
-        trap_if(ptr + len(encoded) > len(cx.opts.memory))
       tagged_code_units = int(len(encoded) / 2) | utf16_tag(cx.opts.memory.ptr_type())
       return (ptr, tagged_code_units)
   if dst_byte_length < src_code_units:
     ptr = cx.reallocate(ptr, src_code_units, 2, dst_byte_length)
-    trap_if(ptr != align_to(ptr, 2))
-    trap_if(ptr + dst_byte_length > len(cx.opts.memory))
   return (ptr, dst_byte_length)
 ```
 
@@ -2738,8 +2723,6 @@ def store_probably_utf16_to_latin1_or_utf16(cx, src, src_code_units):
   src_byte_length = 2 * src_code_units
   assert(src_byte_length <= REALLOC_I32_MAX)
   ptr = cx.allocate(2, src_byte_length)
-  trap_if(ptr != align_to(ptr, 2))
-  trap_if(ptr + src_byte_length > len(cx.opts.memory))
   encoded = src.encode('utf-16-le')
   cx.opts.memory[ptr : ptr+len(encoded)] = encoded
   if any(ord(c) >= (1 << 8) for c in src):
@@ -2748,8 +2731,7 @@ def store_probably_utf16_to_latin1_or_utf16(cx, src, src_code_units):
   latin1_size = int(len(encoded) / 2)
   for i in range(latin1_size):
     cx.opts.memory[ptr + i] = cx.opts.memory[ptr + 2*i]
-  ptr = cx.reallocate(ptr, src_byte_length, 1, latin1_size)
-  trap_if(ptr + latin1_size > len(cx.opts.memory))
+  ptr = cx.reallocate(ptr, src_byte_length, 2, latin1_size)
   return (ptr, latin1_size)
 ```
 
@@ -2780,8 +2762,6 @@ def store_list_into_range(cx, v, elem_type):
   byte_length = len(v) * elem_size(elem_type, cx.opts.memory.ptr_type())
   assert(byte_length <= REALLOC_I32_MAX)
   ptr = cx.allocate(alignment(elem_type, cx.opts.memory.ptr_type()), byte_length)
-  trap_if(ptr != align_to(ptr, alignment(elem_type, cx.opts.memory.ptr_type())))
-  trap_if(ptr + byte_length > len(cx.opts.memory))
   store_list_into_valid_range(cx, v, ptr, elem_type)
   return (ptr, len(v))
 
@@ -3317,9 +3297,9 @@ def lower_flat_values(cx, max_flat, vs, ts, out_param = None):
       flat_vals = [ptr]
     else:
       ptr = out_param.next(cx.opts.memory.ptr_type())
+      trap_if(ptr != align_to(ptr, alignment(tuple_type, cx.opts.memory.ptr_type())))
+      trap_if(ptr + elem_size(tuple_type, cx.opts.memory.ptr_type()) > len(cx.opts.memory))
       flat_vals = []
-    trap_if(ptr != align_to(ptr, alignment(tuple_type, cx.opts.memory.ptr_type())))
-    trap_if(ptr + elem_size(tuple_type, cx.opts.memory.ptr_type()) > len(cx.opts.memory))
     store(cx, tuple_value, tuple_type, ptr)
   else:
     flat_vals = []
diff --git a/design/mvp/canonical-abi/definitions.py b/design/mvp/canonical-abi/definitions.py
index ff2e29e5..70ae3bc4 100644
--- a/design/mvp/canonical-abi/definitions.py
+++ b/design/mvp/canonical-abi/definitions.py
@@ -638,6 +638,8 @@ def on_resolve(result):
     self.inst.store.invoke(realloc, on_start, on_resolve)
     self.inst.may_leave = True
     assert(ptr is not None)
+    trap_if(ptr != align_to(ptr, alignment))
+    trap_if(ptr + new_byte_length > len(self.opts.memory))
     return ptr
 
   def allocate(self, alignment, byte_length):
@@ -1574,8 +1576,6 @@ def store_string_copy(cx, src, src_code_units, dst_code_unit_size, dst_alignment
   dst_byte_length = dst_code_unit_size * src_code_units
   assert(dst_byte_length <= REALLOC_I32_MAX)
   ptr = cx.allocate(dst_alignment, dst_byte_length)
-  trap_if(ptr != align_to(ptr, dst_alignment))
-  trap_if(ptr + dst_byte_length > len(cx.opts.memory))
   encoded = src.encode(dst_encoding)
   assert(dst_byte_length == len(encoded))
   cx.opts.memory[ptr : ptr+len(encoded)] = encoded
@@ -1592,19 +1592,16 @@ def store_latin1_to_utf8(cx, src, src_code_units):
 def store_string_to_utf8(cx, src, src_code_units, worst_case_size):
   assert(src_code_units <= REALLOC_I32_MAX)
   ptr = cx.allocate(1, src_code_units)
-  trap_if(ptr + src_code_units > len(cx.opts.memory))
   for i,code_point in enumerate(src):
     if ord(code_point) < 2**7:
       cx.opts.memory[ptr + i] = ord(code_point)
     else:
       assert(worst_case_size <= REALLOC_I32_MAX)
       ptr = cx.reallocate(ptr, src_code_units, 1, worst_case_size)
-      trap_if(ptr + worst_case_size > len(cx.opts.memory))
       encoded = src.encode('utf-8')
       cx.opts.memory[ptr+i : ptr+len(encoded)] = encoded[i : ]
       if worst_case_size > len(encoded):
         ptr = cx.reallocate(ptr, worst_case_size, 1, len(encoded))
-        trap_if(ptr + len(encoded) > len(cx.opts.memory))
       return (ptr, len(encoded))
   return (ptr, src_code_units)
 
@@ -1612,22 +1609,16 @@ def store_utf8_to_utf16(cx, src, src_code_units):
   worst_case_size = 2 * src_code_units
   assert(worst_case_size <= REALLOC_I32_MAX)
   ptr = cx.allocate(2, worst_case_size)
-  trap_if(ptr != align_to(ptr, 2))
-  trap_if(ptr + worst_case_size > len(cx.opts.memory))
   encoded = src.encode('utf-16-le')
   cx.opts.memory[ptr : ptr+len(encoded)] = encoded
   if len(encoded) < worst_case_size:
     ptr = cx.reallocate(ptr, worst_case_size, 2, len(encoded))
-    trap_if(ptr != align_to(ptr, 2))
-    trap_if(ptr + len(encoded) > len(cx.opts.memory))
   code_units = int(len(encoded) / 2)
   return (ptr, code_units)
 
 def store_string_to_latin1_or_utf16(cx, src, src_code_units):
   assert(src_code_units <= REALLOC_I32_MAX)
   ptr = cx.allocate(2, src_code_units)
-  trap_if(ptr != align_to(ptr, 2))
-  trap_if(ptr + src_code_units > len(cx.opts.memory))
   dst_byte_length = 0
   for usv in src:
     if ord(usv) < (1 << 8):
@@ -1637,8 +1628,6 @@ def store_string_to_latin1_or_utf16(cx, src, src_code_units):
       worst_case_size = 2 * src_code_units
       assert(worst_case_size <= REALLOC_I32_MAX)
       ptr = cx.reallocate(ptr, src_code_units, 2, worst_case_size)
-      trap_if(ptr != align_to(ptr, 2))
-      trap_if(ptr + worst_case_size > len(cx.opts.memory))
       for j in range(dst_byte_length-1, -1, -1):
         cx.opts.memory[ptr + 2*j] = cx.opts.memory[ptr + j]
         cx.opts.memory[ptr + 2*j + 1] = 0
@@ -1646,22 +1635,16 @@ def store_string_to_latin1_or_utf16(cx, src, src_code_units):
       cx.opts.memory[ptr+2*dst_byte_length : ptr+len(encoded)] = encoded[2*dst_byte_length : ]
       if worst_case_size > len(encoded):
         ptr = cx.reallocate(ptr, worst_case_size, 2, len(encoded))
-        trap_if(ptr != align_to(ptr, 2))
-        trap_if(ptr + len(encoded) > len(cx.opts.memory))
       tagged_code_units = int(len(encoded) / 2) | utf16_tag(cx.opts.memory.ptr_type())
       return (ptr, tagged_code_units)
   if dst_byte_length < src_code_units:
     ptr = cx.reallocate(ptr, src_code_units, 2, dst_byte_length)
-    trap_if(ptr != align_to(ptr, 2))
-    trap_if(ptr + dst_byte_length > len(cx.opts.memory))
   return (ptr, dst_byte_length)
 
 def store_probably_utf16_to_latin1_or_utf16(cx, src, src_code_units):
   src_byte_length = 2 * src_code_units
   assert(src_byte_length <= REALLOC_I32_MAX)
   ptr = cx.allocate(2, src_byte_length)
-  trap_if(ptr != align_to(ptr, 2))
-  trap_if(ptr + src_byte_length > len(cx.opts.memory))
   encoded = src.encode('utf-16-le')
   cx.opts.memory[ptr : ptr+len(encoded)] = encoded
   if any(ord(c) >= (1 << 8) for c in src):
@@ -1670,8 +1653,7 @@ def store_probably_utf16_to_latin1_or_utf16(cx, src, src_code_units):
   latin1_size = int(len(encoded) / 2)
   for i in range(latin1_size):
     cx.opts.memory[ptr + i] = cx.opts.memory[ptr + 2*i]
-  ptr = cx.reallocate(ptr, src_byte_length, 1, latin1_size)
-  trap_if(ptr + latin1_size > len(cx.opts.memory))
+  ptr = cx.reallocate(ptr, src_byte_length, 2, latin1_size)
   return (ptr, latin1_size)
 
 def lower_error_context(cx, v):
@@ -1690,8 +1672,6 @@ def store_list_into_range(cx, v, elem_type):
   byte_length = len(v) * elem_size(elem_type, cx.opts.memory.ptr_type())
   assert(byte_length <= REALLOC_I32_MAX)
   ptr = cx.allocate(alignment(elem_type, cx.opts.memory.ptr_type()), byte_length)
-  trap_if(ptr != align_to(ptr, alignment(elem_type, cx.opts.memory.ptr_type())))
-  trap_if(ptr + byte_length > len(cx.opts.memory))
   store_list_into_valid_range(cx, v, ptr, elem_type)
   return (ptr, len(v))
 
@@ -2059,9 +2039,9 @@ def lower_flat_values(cx, max_flat, vs, ts, out_param = None):
       flat_vals = [ptr]
     else:
       ptr = out_param.next(cx.opts.memory.ptr_type())
+      trap_if(ptr != align_to(ptr, alignment(tuple_type, cx.opts.memory.ptr_type())))
+      trap_if(ptr + elem_size(tuple_type, cx.opts.memory.ptr_type()) > len(cx.opts.memory))
       flat_vals = []
-    trap_if(ptr != align_to(ptr, alignment(tuple_type, cx.opts.memory.ptr_type())))
-    trap_if(ptr + elem_size(tuple_type, cx.opts.memory.ptr_type()) > len(cx.opts.memory))
     store(cx, tuple_value, tuple_type, ptr)
   else:
     flat_vals = []