diff --git a/maintainers/scripts/update.nix b/maintainers/scripts/update.nix
index bbc3004b1c4..7c45e148e82 100755
--- a/maintainers/scripts/update.nix
+++ b/maintainers/scripts/update.nix
@@ -2,6 +2,7 @@
 , maintainer ? null
 , path ? null
 , max-workers ? null
+, include-overlays ? false
 , keep-going ? null
 }:
 
@@ -20,9 +21,7 @@ let
       in
         [x] ++ nubOn f xs;
 
-  pkgs = import ./../../default.nix {
-    overlays = [];
-  };
+  pkgs = import ./../../default.nix (if include-overlays then { } else { overlays = []; });
 
   packagesWith = cond: return: set:
     nubOn (pkg: pkg.updateScript)
diff --git a/pkgs/common-updater/scripts/update-source-version b/pkgs/common-updater/scripts/update-source-version
index 7fb5e413a26..6a66f94597f 100755
--- a/pkgs/common-updater/scripts/update-source-version
+++ b/pkgs/common-updater/scripts/update-source-version
@@ -144,6 +144,10 @@ if [[ -n "$sri" ]]; then
     tempHash="$(nix to-sri --type "$oldHashAlgo" "$tempHash")"
 fi
 
+# Escape regex metacharacter that are allowed in hashes (+)
+oldHashEscaped=$(echo "$oldHash" | sed -re 's|[+]|\\&|g')
+tempHashEscaped=$(echo "$tempHash" | sed -re 's|[+]|\\&|g')
+
 # Replace new version
 sed -i.bak "$nixFile" -re "$pattern"
 if cmp -s "$nixFile" "$nixFile.bak"; then
@@ -159,7 +163,7 @@ if [[ -n "$newUrl" ]]; then
     fi
 fi
 
-sed -i "$nixFile" -re "s|\"$oldHash\"|\"$tempHash\"|"
+sed -i "$nixFile" -re "s|\"$oldHashEscaped\"|\"$tempHash\"|"
 if cmp -s "$nixFile" "$nixFile.bak"; then
     die "Failed to replace source hash of '$attr' to a temporary hash!"
 fi
@@ -168,12 +172,12 @@ fi
 if [[ -z "$newHash" ]]; then
     nix-build $systemArg --no-out-link -A "$attr.src" 2>"$attr.fetchlog" >/dev/null || true
     # FIXME: use nix-build --hash here once https://github.com/NixOS/nix/issues/1172 is fixed
-    newHash=$(grep --extended-regexp --invert-match "killing process|dependencies couldn't be built|wanted: " "$attr.fetchlog" | tail -n2 | sed "s~output path .* has .* hash ‘\(.*\)’ when .* was expected\|fixed-output derivation produced path '.*' with .* hash '\(.*\)' instead of the expected hash '.*'\|  got:    .*:\(.*\)~\1\2\3~" | head -n1)
-fi
+    newHash=$(sed '1,/hash mismatch in fixed-output derivation/d' "$attr.fetchlog" | grep --perl-regexp --only-matching 'got: +.+[:-]\K.+')
 
-if [[ -n "$sri" ]]; then
-    # nix-build preserves the hashing scheme so we can just convert the result to SRI using the old type
-    newHash="$(nix to-sri --type "$oldHashAlgo" "$newHash")"
+    if [[ -n "$sri" ]]; then
+        # nix-build preserves the hashing scheme so we can just convert the result to SRI using the old type
+        newHash="$(nix to-sri --type "$oldHashAlgo" "$newHash")"
+    fi
 fi
 
 if [[ -z "$newHash" ]]; then
@@ -186,7 +190,7 @@ if [[ -z "${ignoreSameHash}" && "$oldVersion" != "$newVersion" && "$oldHash" = "
     die "Both the old and new source hashes of '$attr.src' were equivalent. Please fix the package's source URL to be dependent on '\${version}'!"
 fi
 
-sed -i "$nixFile" -re "s|\"$tempHash\"|\"$newHash\"|"
+sed -i "$nixFile" -re "s|\"$tempHashEscaped\"|\"$newHash\"|"
 if cmp -s "$nixFile" "$nixFile.bak"; then
     die "Failed to replace temporary source hash of '$attr' to the final source hash!"
 fi