diff --git a/lib/less/contexts.js b/lib/less/contexts.js
index 829760a6e..803b8c6c9 100644
--- a/lib/less/contexts.js
+++ b/lib/less/contexts.js
@@ -84,7 +84,7 @@ contexts.Eval = class {
 
     exitCalc() {
         this.calcStack.pop();
-        if (!this.calcStack) {
+        if (!this.calcStack.length) {
             this.inCalc = false;
         }
     }
diff --git a/test/css/calc.css b/test/css/calc.css
index 9b29d7bf8..7f335c69b 100644
--- a/test/css/calc.css
+++ b/test/css/calc.css
@@ -17,3 +17,12 @@
 .c {
   height: calc(100% - ((10px * 3) + (10px * 2)));
 }
+.correctly-exit-calc-mode h2 {
+  width: 10px;
+}
+.correctly-exit-calc-mode div {
+  width: calc(100px * 2);
+}
+.correctly-exit-calc-mode h1 {
+  color: white;
+}
diff --git a/test/less/calc.less b/test/less/calc.less
index 53142290a..8bdf57b61 100644
--- a/test/less/calc.less
+++ b/test/less/calc.less
@@ -27,4 +27,20 @@
 .c {
   @v: 10px;
   height: calc(100% - ((@v * 3) + (@v * 2)));
-}
\ No newline at end of file
+}
+
+.correctly-exit-calc-mode {
+    @a: 10;
+    h2 { width: unit(@a, px); }
+
+    div { width: calc(100px * 2); }
+
+    .mk-map() {
+        text: white;
+        background: black;
+    }
+
+    @p: .mk-map();
+
+    h1 { color: @p[text]; }
+}
diff --git a/test/sourcemaps/custom-props.json b/test/sourcemaps/custom-props.json
index 286846f5b..cb6fb6abe 100644
--- a/test/sourcemaps/custom-props.json
+++ b/test/sourcemaps/custom-props.json
@@ -1 +1 @@
-{"version":3,"sources":["testweb/sourcemaps/custom-props.less"],"names":[],"mappings":"AAEA;EACC,uBAHO,UAGP;EACA,OAAO,eAAP;EACA,gCAAA","file":"sourcemaps/custom-props.css"}
\ No newline at end of file
+{"version":3,"sources":["testweb/sourcemaps/custom-props.less"],"names":[],"mappings":"AAEA;EACC,uBAHO,UAGP;EACA,OAAO,eAAP;EACA,sBALO,UAKP","file":"sourcemaps/custom-props.css"}
\ No newline at end of file