diff --git a/modules/programs/zsh.nix b/modules/programs/zsh.nix
index b6e46392c..1a915940c 100644
--- a/modules/programs/zsh.nix
+++ b/modules/programs/zsh.nix
@@ -713,7 +713,7 @@ in
           ZSH_HIGHLIGHT_HIGHLIGHTERS+=(${lib.concatStringsSep " " (map lib.escapeShellArg cfg.syntaxHighlighting.highlighters)})
           ${lib.concatStringsSep "\n" (
               lib.mapAttrsToList
-                (name: value: "ZSH_HIGHLIGHT_STYLES+=(${lib.escapeShellArg name} ${lib.escapeShellArg value})")
+		(name: value: "ZSH_HIGHLIGHT_STYLES[${lib.escapeShellArg name}]=${lib.escapeShellArg value}")
                 cfg.syntaxHighlighting.styles
           )}
           ${lib.concatStringsSep "\n" (
diff --git a/tests/modules/programs/zsh/syntax-highlighting.nix b/tests/modules/programs/zsh/syntax-highlighting.nix
index 052b228bd..b382a7118 100644
--- a/tests/modules/programs/zsh/syntax-highlighting.nix
+++ b/tests/modules/programs/zsh/syntax-highlighting.nix
@@ -20,7 +20,7 @@ with lib;
     nmt.script = ''
       assertFileContains home-files/.zshrc "source ${pkgs.hello}/share/zsh-syntax-highlighting/zsh-syntax-highlighting.zsh"
       assertFileContains home-files/.zshrc "ZSH_HIGHLIGHT_HIGHLIGHTERS+=(brackets pattern cursor)"
-      assertFileContains home-files/.zshrc "ZSH_HIGHLIGHT_STYLES+=(comment 'fg=#6c6c6c')"
+      assertFileContains home-files/.zshrc "ZSH_HIGHLIGHT_STYLES[comment]='fg=#6c6c6c'"
     '';
   };
 }