diff --git a/History.md b/History.md
index 630a2f912..12f43ad8b 100644
--- a/History.md
+++ b/History.md
@@ -1,3 +1,8 @@
+[4.2.3 / 2020-xx-xx](https://github.com/jakubpawlowicz/clean-css/compare/v4.2.2...4.2)
+==================
+
+* Fixed issue [#1106](https://github.com/jakubpawlowicz/clean-css/issues/1106) - regression in handling RGBA/HSLA colors.
+
 [4.2.2 / 2020-01-25](https://github.com/jakubpawlowicz/clean-css/compare/v4.2.1...v4.2.2)
 ==================
 
diff --git a/lib/optimizer/level-1/optimize.js b/lib/optimizer/level-1/optimize.js
index 5131be052..fe2aec040 100644
--- a/lib/optimizer/level-1/optimize.js
+++ b/lib/optimizer/level-1/optimize.js
@@ -106,7 +106,7 @@ function optimizeColors(name, value, compatibility) {
   }
 
   value = value
-    .replace(/(rgb|hsl)a?\((\-?\d+),(\-?\d+\%?),(\-?\d+\%?),(0*[1-9]+[0-9]*(.?\d*)?)\)/gi, function (match, colorFn, p1, p2, p3, alpha) {
+    .replace(/(rgb|hsl)a?\((\-?\d+),(\-?\d+\%?),(\-?\d+\%?),(0*[1-9]+[0-9]*(\.?\d*)?)\)/gi, function (match, colorFn, p1, p2, p3, alpha) {
       return (parseInt(alpha, 10) >= 1 ? colorFn + '(' + [p1,p2,p3].join(',') + ')' : match);
     })
     .replace(/rgb\((\-?\d+),(\-?\d+),(\-?\d+)\)/gi, function (match, red, green, blue) {
diff --git a/test/optimizer/level-1/optimize-test.js b/test/optimizer/level-1/optimize-test.js
index 91d33261e..f12c3dcf7 100644
--- a/test/optimizer/level-1/optimize-test.js
+++ b/test/optimizer/level-1/optimize-test.js
@@ -412,6 +412,10 @@ vows.describe('level 1 optimizations')
       '8-value hex': [
         '.block{color:#00ff0080}',
         '.block{color:#00ff0080}'
+      ],
+      'rgba inside a function': [
+        '.block{background-image:linear-gradient(to right,rgba(255,255,255,0),rgba(255,255,255,1))}',
+        '.block{background-image:linear-gradient(to right,rgba(255,255,255,0),#fff)}'
       ]
     }, { level: 1 })
   )