diff --git a/antigen.zsh b/antigen.zsh
index 2c736b7..04d8b80 100644
--- a/antigen.zsh
+++ b/antigen.zsh
@@ -621,7 +621,8 @@ antigen () {
         fi
 
         # The specification for this argument, used for validations.
-        local arg_line="$(echo "$keyword_args" | egrep "^$name:?\??" | head -n1)"
+        local arg_line="$(echo "$keyword_args" |
+                            egrep "^$name:?\??" | head -n1)"
 
         # Validate argument and value.
         if [[ -z $arg_line ]]; then
@@ -629,12 +630,14 @@ antigen () {
             echo "Unknown argument '$name'." >&2
             return
 
-        elif (echo "$arg_line" | grep -l ':' &> /dev/null) && [[ -z $value ]]; then
+        elif (echo "$arg_line" | grep -l ':' &> /dev/null) &&
+                [[ -z $value ]]; then
             # This argument needs a value, but is not provided.
             echo "Required argument for '$name' not provided." >&2
             return
 
-        elif (echo "$arg_line" | grep -vl ':' &> /dev/null) && [[ ! -z $value ]]; then
+        elif (echo "$arg_line" | grep -vl ':' &> /dev/null) &&
+                [[ -n $value ]]; then
             # This argument doesn't need a value, but is provided.
             echo "No argument required for '$name', but provided '$value'." >&2
             return