diff --git a/src/libstore/nar-info.cc b/src/libstore/nar-info.cc
index a90812ff9..708cc7341 100644
--- a/src/libstore/nar-info.cc
+++ b/src/libstore/nar-info.cc
@@ -146,6 +146,8 @@ nlohmann::json NarInfo::toJSON(
     if (includeImpureInfo) {
         if (!url.empty())
             jsonObject["url"] = url;
+        if (!compression.empty())
+            jsonObject["compression"] = compression;
         if (fileHash)
             jsonObject["downloadHash"] = fileHash->to_string(hashFormat, true);
         if (fileSize)
@@ -168,6 +170,9 @@ NarInfo NarInfo::fromJSON(
     if (json.contains("url"))
         res.url = ensureType(valueAt(json, "url"), value_t::string);
 
+    if (json.contains("compression"))
+        res.compression = ensureType(valueAt(json, "compression"), value_t::string);
+
     if (json.contains("downloadHash"))
         res.fileHash = Hash::parseAny(
             static_cast<const std::string &>(
diff --git a/src/libstore/tests/nar-info.cc b/src/libstore/tests/nar-info.cc
index cb92f3a28..c5b21d56b 100644
--- a/src/libstore/tests/nar-info.cc
+++ b/src/libstore/tests/nar-info.cc
@@ -48,6 +48,7 @@ static NarInfo makeNarInfo(const Store & store, bool includeImpureInfo) {
         info.sigs = { "asdf", "qwer" };
 
         info.url = "nar/1w1fff338fvdw53sqgamddn1b2xgds473pv6y13gizdbqjv4i5p3.nar.xz";
+        info.compression = "xz";
         info.fileHash = Hash::parseSRI("sha256-FePFYIlMuycIXPZbWi7LGEiMmZSX9FMbaQenWBzm1Sc=");
         info.fileSize = 4029176;
     }
diff --git a/unit-test-data/libstore/nar-info/impure.json b/unit-test-data/libstore/nar-info/impure.json
index 093f25025..3f16667c9 100644
--- a/unit-test-data/libstore/nar-info/impure.json
+++ b/unit-test-data/libstore/nar-info/impure.json
@@ -1,5 +1,6 @@
 {
   "ca": "fixed:r:sha256:1lr187v6dck1rjh2j6svpikcfz53wyl3qrlcbb405zlh13x0khhh",
+  "compression": "xz",
   "deriver": "/nix/store/g1w7hy3qg1w7hy3qg1w7hy3qg1w7hy3q-bar.drv",
   "downloadHash": "sha256-FePFYIlMuycIXPZbWi7LGEiMmZSX9FMbaQenWBzm1Sc=",
   "downloadSize": 4029176,