diff --git a/spacy/cli/init_model.py b/spacy/cli/init_model.py
index 5f06fd895..9eab7b54d 100644
--- a/spacy/cli/init_model.py
+++ b/spacy/cli/init_model.py
@@ -256,6 +256,7 @@ def add_vectors(
 
 def read_vectors(msg: Printer, vectors_loc: Path, truncate_vectors: int):
     f = open_file(vectors_loc)
+    f = ensure_shape(f)
     shape = tuple(int(size) for size in next(f).split())
     if truncate_vectors >= 1:
         shape = (truncate_vectors, shape[1])
@@ -274,6 +275,31 @@ def read_vectors(msg: Printer, vectors_loc: Path, truncate_vectors: int):
     return vectors_data, vectors_keys
 
 
+def ensure_shape(lines):
+    """Ensure that the first line of the data is the vectors shape.
+    
+    If it's not, we read in the data and output the shape as the first result,
+    so that the reader doesn't have to deal with the problem.
+    """
+    first_line = next(lines)
+    try:
+        shape = tuple(int(size) for size in first_line.split())
+    except ValueError:
+        shape = None
+    if shape is not None:
+        # All good, give the data
+        yield first_line
+        yield from lines
+    else:
+        # Figure out the shape, make it the first value, and then give the
+        # rest of the data.
+        width = len(first_line.split()) - 1
+        captured = [first_line] + list(lines)
+        length = len(captured)
+        yield f"{length} {width}"
+        yield from captured
+
+
 def read_freqs(
     freqs_loc: Path, max_length: int = 100, min_doc_freq: int = 5, min_freq: int = 50
 ):