diff --git a/src/main/java/io/airlift/compress/v3/zstd/ZstdNative.java b/src/main/java/io/airlift/compress/v3/zstd/ZstdNative.java
index 37631a88..aecf0bd1 100644
--- a/src/main/java/io/airlift/compress/v3/zstd/ZstdNative.java
+++ b/src/main/java/io/airlift/compress/v3/zstd/ZstdNative.java
@@ -154,7 +154,8 @@ public static long decompressedLength(MemorySegment compressed, long compressedL
             throw new Error("Unexpected exception", e);
         }
 
-        if (isError(result)) {
+        // -1 is valid return for content size unknown
+        if (result < -1) {
             throw new IllegalArgumentException("Unknown error occurred during decompression: " + getErrorName(result));
         }
         return result;