diff --git a/lib/strings.nix b/lib/strings.nix
index 5fba13822e3f..edc31b4e9e36 100644
--- a/lib/strings.nix
+++ b/lib/strings.nix
@@ -395,7 +395,7 @@ rec {
   */
   toShellVar = name: value:
     lib.throwIfNot (isValidPosixName name) "toShellVar: ${name} is not a valid shell variable name" (
-    if isAttrs value && ! isCoercibleToString value then
+    if isAttrs value && ! isSimpleCoercibleToString value then
       "declare -A ${name}=(${
         concatStringsSep " " (lib.mapAttrsToList (n: v:
           "[${escapeShellArg n}]=${escapeShellArg v}"