diff --git a/lib/lexer.js b/lib/lexer.js
index 91b1928c..f55c7628 100644
--- a/lib/lexer.js
+++ b/lib/lexer.js
@@ -622,7 +622,7 @@
   MULTI_DENT = /^(?:\n[^\n\S]*)+/;
   SIMPLESTR = /^'[^\\']*(?:\\.[^\\']*)*'/;
   JSTOKEN = /^`[^\\`]*(?:\\.[^\\`]*)*`/;
-  REGEX = /^\/(?!\s)[^[\/\n\\]*(?:(?:\\[\s\S]|\[[^\]\n\\]*(?:\\[\s\S][^\]\n\\]*)*])[^[\/\n\\]*)*\/[imgy]{0,4}(?![A-Za-z])/;
+  REGEX = /^\/(?!\s)[^[\/\n\\]*(?:(?:\\[\s\S]|\[[^\]\n\\]*(?:\\[\s\S][^\]\n\\]*)*])[^[\/\n\\]*)*\/[imgy]{0,4}(?![A-Za-z0-9])/;
   HEREGEX = /^\/{3}([\s\S]+?)\/{3}([imgy]{0,4})(?![A-Za-z])/;
   HEREGEX_OMIT = /\s+(?:#.*)?/g;
   MULTILINER = /\n/g;
diff --git a/src/lexer.coffee b/src/lexer.coffee
index 82c08716..eb6f035f 100644
--- a/src/lexer.coffee
+++ b/src/lexer.coffee
@@ -584,7 +584,7 @@ REGEX = /// ^
          ]
     ) [^ [ / \n \\ ]*
   )*
-  / [imgy]{0,4} (?![A-Za-z])
+  / [imgy]{0,4} (?![A-Za-z0-9])
 ///
 
 HEREGEX      = /^\/{3}([\s\S]+?)\/{3}([imgy]{0,4})(?![A-Za-z])/