diff --git a/src/libfetchers/fetchers.cc b/src/libfetchers/fetchers.cc
index 976f40d3b..6957d2da4 100644
--- a/src/libfetchers/fetchers.cc
+++ b/src/libfetchers/fetchers.cc
@@ -238,9 +238,18 @@ std::optional<std::string> Input::getRef() const
 
 std::optional<Hash> Input::getRev() const
 {
-    if (auto s = maybeGetStrAttr(attrs, "rev"))
-        return Hash::parseAny(*s, htSHA1);
-    return {};
+    std::optional<Hash> hash = {};
+
+    if (auto s = maybeGetStrAttr(attrs, "rev")) {
+        try {
+            hash = Hash::parseAnyPrefixed(*s);
+        } catch (BadHash &e) {
+            // Default to sha1 for backwards compatibility with existing flakes
+            hash = Hash::parseAny(*s, htSHA1);
+        }
+    }
+
+    return hash;
 }
 
 std::optional<uint64_t> Input::getRevCount() const
diff --git a/src/libutil/hash.cc b/src/libutil/hash.cc
index a4d632161..d2fd0c15a 100644
--- a/src/libutil/hash.cc
+++ b/src/libutil/hash.cc
@@ -155,7 +155,7 @@ static std::pair<std::optional<HashType>, bool> getParsedTypeAndSRI(std::string_
 {
     bool isSRI = false;
 
-    // Parse the has type before the separater, if there was one.
+    // Parse the hash type before the separator, if there was one.
     std::optional<HashType> optParsedType;
     {
         auto hashRaw = splitPrefixTo(rest, ':');
diff --git a/src/libutil/hash.hh b/src/libutil/hash.hh
index 56b5938b3..00f70a572 100644
--- a/src/libutil/hash.hh
+++ b/src/libutil/hash.hh
@@ -93,13 +93,11 @@ public:
 
     std::string gitRev() const
     {
-        assert(type == htSHA1);
         return to_string(Base16, false);
     }
 
     std::string gitShortRev() const
     {
-        assert(type == htSHA1);
         return std::string(to_string(Base16, false), 0, 7);
     }