diff --git a/lib-es5/utils/index.js b/lib-es5/utils/index.js
index c8be7271..009f9e69 100644
--- a/lib-es5/utils/index.js
+++ b/lib-es5/utils/index.js
@@ -137,12 +137,20 @@ function normalize_expression(expression) {
   if (!isString(expression) || expression.length === 0 || expression.match(/^!.+!$/)) {
     return expression;
   }
+
   var operators = "\\|\\||>=|<=|&&|!=|>|=|<|/|-|\\+|\\*";
-  var pattern = "((" + operators + ")(?=[ _])|" + Object.keys(PREDEFINED_VARS).join("|") + ")";
-  var replaceRE = new RegExp(pattern, "g");
-  expression = expression.replace(replaceRE, function (match) {
-    return CONDITIONAL_OPERATORS[match] || PREDEFINED_VARS[match];
+  var operatorsPattern = "((" + operators + ")(?=[ _]))";
+  var operatorsReplaceRE = new RegExp(operatorsPattern, "g");
+  expression = expression.replace(operatorsReplaceRE, function (match) {
+    return CONDITIONAL_OPERATORS[match];
+  });
+
+  var predefinedVarsPattern = "(" + Object.keys(PREDEFINED_VARS).join("|") + ")";
+  var predefinedVarsReplaceRE = new RegExp(predefinedVarsPattern, "g");
+  expression = expression.replace(predefinedVarsReplaceRE, function (match, p1, offset) {
+    return expression[offset - 1] === '$' ? match : PREDEFINED_VARS[match];
   });
+
   return expression.replace(/[ _]+/g, '_');
 }
 
diff --git a/lib/utils/index.js b/lib/utils/index.js
index be7f0ce1..1752cacc 100644
--- a/lib/utils/index.js
+++ b/lib/utils/index.js
@@ -127,12 +127,16 @@ function normalize_expression(expression) {
   if (!isString(expression) || expression.length === 0 || expression.match(/^!.+!$/)) {
     return expression;
   }
+
   const operators = "\\|\\||>=|<=|&&|!=|>|=|<|/|-|\\+|\\*";
-  const pattern = "((" + operators + ")(?=[ _])|" + Object.keys(PREDEFINED_VARS).join("|") + ")";
-  const replaceRE = new RegExp(pattern, "g");
-  expression = expression.replace(replaceRE, function (match) {
-    return CONDITIONAL_OPERATORS[match] || PREDEFINED_VARS[match];
-  });
+  const operatorsPattern = "((" + operators + ")(?=[ _]))";
+  const operatorsReplaceRE = new RegExp(operatorsPattern, "g");
+  expression = expression.replace(operatorsReplaceRE, match => CONDITIONAL_OPERATORS[match]);
+
+  const predefinedVarsPattern = "(" + Object.keys(PREDEFINED_VARS).join("|") + ")";
+  const predefinedVarsReplaceRE = new RegExp(predefinedVarsPattern, "g");
+  expression = expression.replace(predefinedVarsReplaceRE, (match, p1, offset) => (expression[offset - 1] === '$' ? match : PREDEFINED_VARS[match]));
+
   return expression.replace(/[ _]+/g, '_');
 }
 
diff --git a/test/utils_spec.js b/test/utils_spec.js
index adfc4dff..ca32422e 100644
--- a/test/utils_spec.js
+++ b/test/utils_spec.js
@@ -1052,6 +1052,21 @@ describe("utils", function () {
         t = cloudinary.utils.generate_transformation_string(options);
         expect(t).to.eql("$foo_10/if_fc_gt_2/c_scale,w_$foo_mul_200_div_fc/if_end");
       });
+      it("should not change variable names even if they look like keywords", function () {
+        var options, t;
+        options = {
+          transformation: [
+            {
+              $width: 10,
+            },
+            {
+              width: "$width + 10 + width",
+            },
+          ],
+        };
+        t = cloudinary.utils.generate_transformation_string(options);
+        expect(t).to.eql("$width_10/w_$width_add_10_add_w");
+      });
       it("should support text values", function () {
         test_cloudinary_url("sample", {
           effect: "$efname:100",