diff --git a/src/crystal/system/unix/getrandom.cr b/src/crystal/system/unix/getrandom.cr
index 229716a3d846..e759ff0406e6 100644
--- a/src/crystal/system/unix/getrandom.cr
+++ b/src/crystal/system/unix/getrandom.cr
@@ -13,7 +13,10 @@ require "./syscall"
 
     # TODO: Implement syscall for interpreter
     def self.getrandom(buf : UInt8*, buflen : LibC::SizeT, flags : UInt32) : LibC::SSizeT
-      LibC.getrandom(buf, buflen, flags)
+      # the syscall returns the negative of errno directly, the C function
+      # doesn't, so we mimic the syscall behavior
+      read_bytes = LibC.getrandom(buf, buflen, flags)
+      read_bytes >= 0 ? read_bytes : LibC::SSizeT.new(-Errno.value.value)
     end
   end
 {% end %}