diff --git a/.gitignore b/.gitignore
index 518329ca0..8e57ffcf7 100644
--- a/.gitignore
+++ b/.gitignore
@@ -6,6 +6,7 @@
 .idea
 *.iml
 *.sublime-*
+.DS_Store
 
 # npm
 node_modules
diff --git a/packages/less/src/less/parser/parser.js b/packages/less/src/less/parser/parser.js
index d9b1e8137..41b7d01a5 100644
--- a/packages/less/src/less/parser/parser.js
+++ b/packages/less/src/less/parser/parser.js
@@ -1684,7 +1684,7 @@ const Parser = function Parser(context, imports, fileInfo) {
                 let features;
                 const index = parserInput.i;
 
-                const dir = parserInput.$re(/^@import?\s+/);
+                const dir = parserInput.$re(/^@import\s+/);
 
                 if (dir) {
                     const options = (dir ? this.importOptions() : null) || {};
@@ -1844,7 +1844,7 @@ const Parser = function Parser(context, imports, fileInfo) {
                 let args;
                 let options;
                 const index = parserInput.i;
-                const dir   = parserInput.$re(/^@plugin?\s+/);
+                const dir   = parserInput.$re(/^@plugin\s+/);
 
                 if (dir) {
                     args = this.pluginArgs();
diff --git a/packages/test-data/css/_main/impor.css b/packages/test-data/css/_main/impor.css
new file mode 100644
index 000000000..7345719e9
--- /dev/null
+++ b/packages/test-data/css/_main/impor.css
@@ -0,0 +1 @@
+@impor "impor-typo-dont-parse-as-@import.less";
diff --git a/packages/test-data/css/_main/plugi.css b/packages/test-data/css/_main/plugi.css
new file mode 100644
index 000000000..de4c6a02c
--- /dev/null
+++ b/packages/test-data/css/_main/plugi.css
@@ -0,0 +1 @@
+@plugi "plugi-typo-dont-parse-as-@plugin";
diff --git a/packages/test-data/less/_main/impor.less b/packages/test-data/less/_main/impor.less
new file mode 100644
index 000000000..bb5e36b0a
--- /dev/null
+++ b/packages/test-data/less/_main/impor.less
@@ -0,0 +1,5 @@
+// https://github.com/less/less.js/issues/3660
+// const dir = parserInput.$re(/^@import?\s+/);
+// correct regexp is /^@import\s+/
+// so follow code will change nothing, parse result is same with raw less code
+@impor "impor-typo-dont-parse-as-@import.less";
diff --git a/packages/test-data/less/_main/plugi.less b/packages/test-data/less/_main/plugi.less
new file mode 100644
index 000000000..e200eb9f5
--- /dev/null
+++ b/packages/test-data/less/_main/plugi.less
@@ -0,0 +1,5 @@
+// https://github.com/less/less.js/issues/3660
+// const dir = parserInput.$re(/^@plugin?\s+/);
+// correct regexp is /^@plugin\s+/
+// so follow code will change nothing, parse result is same with raw less code
+@plugi "plugi-typo-dont-parse-as-@plugin";