diff --git a/spacy/vocab.pyx b/spacy/vocab.pyx
index f852e67da..9af55790a 100644
--- a/spacy/vocab.pyx
+++ b/spacy/vocab.pyx
@@ -4,6 +4,7 @@ from libc.stdio cimport fopen, fclose, fread, fwrite, FILE
 from libc.string cimport memset
 from libc.stdint cimport int32_t
 from libc.stdint cimport uint64_t
+from libc.math cimport sqrt
 
 import bz2
 from os import path
@@ -386,6 +387,7 @@ cdef class Vocab:
         cdef LexemeC* lexeme
         cdef attr_t orth
         cdef int32_t vec_len = -1
+        cdef double norm = 0.0
         for line_num, line in enumerate(file_):
             pieces = line.split()
             word_str = pieces.pop(0)
@@ -397,9 +399,12 @@ cdef class Vocab:
             orth = self.strings[word_str]
             lexeme = <LexemeC*><void*>self.get_by_orth(self.mem, orth)
             lexeme.vector = <float*>self.mem.alloc(vec_len, sizeof(float))
-
             for i, val_str in enumerate(pieces):
                 lexeme.vector[i] = float(val_str)
+            norm = 0.0
+            for i in range(vec_len):
+                norm += lexeme.vector[i] * lexeme.vector[i]
+            lex.l2_norm = sqrt(norm)
         self.vectors_length = vec_len
         return vec_len
 
@@ -438,14 +443,15 @@ cdef class Vocab:
             line_num += 1
         cdef LexemeC* lex
         cdef size_t lex_addr
+        cdef double norm = 0.0
         cdef int i
         for orth, lex_addr in self._by_orth.items():
             lex = <LexemeC*>lex_addr
             if lex.lower < vectors.size():
                 lex.vector = vectors[lex.lower]
                 for i in range(vec_len):
-                    lex.l2_norm += (lex.vector[i] * lex.vector[i])
-                lex.l2_norm = math.sqrt(lex.l2_norm)
+                    norm += lex.vector[i] * lex.vector[i]
+                lex.l2_norm = sqrt(norm)
             else:
                 lex.vector = EMPTY_VEC
         self.vectors_length = vec_len