diff --git a/README.md b/README.md
index bafebb3..a655b9c 100644
--- a/README.md
+++ b/README.md
@@ -29,10 +29,10 @@ should be using curl directly if your use case is not covered.
 
 * By default, **wcurl** will:    
   * Encode whitespaces in URLs;  
-  * Download multiple URLs in parallel;  
+  * Download multiple URLs in parallel if the installed curl's version is >= 7.66.0;  
   * Follow redirects;  
   * Automatically choose a filename as output;  
-  * Avoid overwriting files if the installed curl version is 7.83 or higher (--no-clobber);  
+  * Avoid overwriting files if the installed curl's version is >= 7.83.0 (--no-clobber);  
   * Perform retries;  
   * Set the downloaded file timestamp to the value provided by the server, if available;  
   * Disable **curl**'s URL globbing parser so **{}** and **\[\]** characters in URLs are not treated specially.
diff --git a/wcurl b/wcurl
index 496b38a..0c2df3a 100755
--- a/wcurl
+++ b/wcurl
@@ -113,17 +113,28 @@ sanitize()
 exec_curl() {
     CMD="curl "
 
-    # Store version to check if it supports --no-clobber.
+    # Store version to check if it supports --no-clobber and --parallel.
     curl_version=$($CMD --version | cut -f2 -d' ' | head -n1)
 
-    # --no-clobber is only supported since 7.83.
+    # --no-clobber is only supported since 7.83.0.
+    # --parallel is only supported since 7.66.0.
     if [ "$(echo "$curl_version" | cut -f1 -d.)" -ge 8 ]; then
-        NO_CLOBBER="--no-clobber"
-    elif [ "$(echo "$curl_version" | cut -f1 -d.)" -eq 7 ] && \
-        [ "$(echo "$curl_version" | cut -f2 -d.)" -ge 83 ]; then
-        NO_CLOBBER="--no-clobber"
+        CURL_HAS_NO_CLOBBER="--no-clobber"
+        CURL_HAS_PARALLEL="--parallel"
+    elif [ "$(echo "$curl_version" | cut -f1 -d.)" -eq 7 ];then
+        if [ "$(echo "$curl_version" | cut -f2 -d.)" -ge 83 ]; then
+            CURL_HAS_NO_CLOBBER="--no-clobber"
+        else
+            CURL_HAS_NO_CLOBBER=""
+        fi
+        if [ "$(echo "$curl_version" | cut -f2 -d.)" -ge 66 ]; then
+            CURL_HAS_PARALLEL="--parallel"
+        else
+            CURL_HAS_PARALLEL=""
+        fi
     else
-        NO_CLOBBER=""
+        CURL_HAS_NO_CLOBBER=""
+        CURL_HAS_PARALLEL=""
     fi
 
     # Detecting whether we need --parallel.  It's easier to rely on
@@ -132,9 +143,9 @@ exec_curl() {
     set -- $URLS
 
     if [ "$#" -gt 1 ]; then
-	CURL_PARALLEL="--parallel"
+        CURL_PARALLEL="$CURL_HAS_PARALLEL"
     else
-	CURL_PARALLEL=""
+        CURL_PARALLEL=""
     fi
 
     # Start assembling the command.
@@ -149,7 +160,7 @@ exec_curl() {
     NEXT_PARAMETER=""
     for url in ${URLS}; do
         # shellcheck disable=SC2086
-        set -- "$@" ${NEXT_PARAMETER} ${PER_URL_PARAMETERS} ${NO_CLOBBER} ${CURL_OPTIONS} "${url}"
+        set -- "$@" ${NEXT_PARAMETER} ${PER_URL_PARAMETERS} ${CURL_HAS_NO_CLOBBER} ${CURL_OPTIONS} "${url}"
         NEXT_PARAMETER="--next"
     done
 
diff --git a/wcurl.1 b/wcurl.1
index e40070e..31622d6 100644
--- a/wcurl.1
+++ b/wcurl.1
@@ -25,13 +25,13 @@ By default, \fBwcurl\fR will:
 .br
 \[bu]  Encode whitespaces in URLs;
 .br
-\[bu]  Download multiple URLs in parallel;
+\[bu]  Download multiple URLs in parallel if the installed curl's version is >= 7.66.0;
 .br
 \[bu]  Follow redirects;
 .br
 \[bu]  Automatically choose a filename as output;
 .br
-\[bu]  Avoid overwriting files if the installed curl version is 7.83 or higher (--no-clobber);
+\[bu]  Avoid overwriting files if the installed curl's version is >= 7.83.0 (--no-clobber);
 .br
 \[bu]  Perform retries;
 .br