diff --git a/algods/algods.py b/algods/algods.py
index 4cab606..0a3367c 100644
--- a/algods/algods.py
+++ b/algods/algods.py
@@ -58,11 +58,20 @@ def min_hash(doc: str, perm: list[str]) -> str:
 
 
 def compute_signature_matrix(shingles: np.ndarray, permutations_count: int) -> np.ndarray:
-    permutation_matrix = np.zeros((permutations_count, len(shingles)))
-    for i in range(permutations_count):
-        permutation_matrix[i] = np.random.permutation(len(shingles))
+    shingles_count, docs_count = shingles.shape
 
-    return permutation_matrix @ shingles
+    signature_matrix = np.inf * np.ones((permutations_count, docs_count))
+
+    for permutation_id in range(permutations_count):
+        permutation = np.random.permutation(shingles_count)
+
+        for doc_id, doc_shingles in enumerate(shingles.T):
+            for x in permutation:
+                if doc_shingles[x]:
+                    signature_matrix[permutation_id, doc_id] = x
+                    break
+
+    return signature_matrix
 
 
 def jaccard_similarity(doc1: set, doc2: set) -> float: