diff --git a/skimage/feature/blob.py b/skimage/feature/blob.py
index bc93d265..5ef5b314 100644
--- a/skimage/feature/blob.py
+++ b/skimage/feature/blob.py
@@ -200,9 +200,11 @@ def blob_dog(image, min_sigma=1, max_sigma=50, sigma_ratio=1.6, threshold=2.0,
                                   footprint=np.ones((3, 3, 3)),
                                   threshold_rel=0.0,
                                   exclude_border=False)
-
+    # Convert array to float32
+    lm = local_maxima.astype('float32')
     # Convert the last index to its corresponding scale value
-    local_maxima[:, 2] = sigma_list[local_maxima[:, 2]]
+    lm[:,2] = sigma_list[local_maxima[:,2]]
+    local_maxima = lm
     return _prune_blobs(local_maxima, overlap)
 
 
@@ -300,8 +302,11 @@ def blob_log(image, min_sigma=1, max_sigma=50, num_sigma=10, threshold=.2,
                                   threshold_rel=0.0,
                                   exclude_border=False)
 
+    # Convert array to float32
+    lm = local_maxima.astype('float32')
     # Convert the last index to its corresponding scale value
-    local_maxima[:, 2] = sigma_list[local_maxima[:, 2]]
+    lm[:,2] = sigma_list[local_maxima[:,2]]
+    local_maxima = lm
     return _prune_blobs(local_maxima, overlap)
 
 
@@ -408,6 +413,9 @@ def blob_doh(image, min_sigma=1, max_sigma=30, num_sigma=10, threshold=0.01,
                                   threshold_rel=0.0,
                                   exclude_border=False)
 
+    # Convert array to float32
+    lm = local_maxima.astype('float32')
     # Convert the last index to its corresponding scale value
-    local_maxima[:, 2] = sigma_list[local_maxima[:, 2]]
+    lm[:,2] = sigma_list[local_maxima[:,2]]
+    local_maxima = lm
     return _prune_blobs(local_maxima, overlap)