diff --git a/src/packages/gfm.tmbundle/Syntaxes/gfm.cson b/src/packages/gfm.tmbundle/Syntaxes/gfm.cson
index 71756f91d..ad88e747f 100644
--- a/src/packages/gfm.tmbundle/Syntaxes/gfm.cson
+++ b/src/packages/gfm.tmbundle/Syntaxes/gfm.cson
@@ -9,20 +9,24 @@
 ]
 'patterns': [
   {
-    'match': '\\*\\*[^\\*]+\\*\\*'
-    'name': 'markup.bold.gfm'
+    'match': '(?:^|\\s)(\\*\\*[^\\*]+\\*\\*)'
+    'captures':
+      '1': 'name': 'markup.bold.gfm'
   }
   {
-    'match': '__[^_]+__'
-    'name': 'markup.bold.gfm'
+    'match': '(?:^|\\s)(__[^_]+__)'
+    'captures':
+      '1': 'name': 'markup.bold.gfm'
   }
   {
-    'match': '\\*[^\\*]+\\*'
-    'name': 'markup.italic.gfm'
+    'match': '(?:^|\\s)(\\*[^\\*]+\\*)'
+    'captures':
+      '1': 'name': 'markup.italic.gfm'
   }
   {
-    'match': '_[^_]+_'
-    'name': 'markup.italic.gfm'
+    'match': '(?:^|\\s)(_[^_]+_)'
+    'captures':
+      '1': 'name': 'markup.italic.gfm'
   }
   {
     'match': '^#{1,6}\\s+.+$'
diff --git a/src/packages/gfm.tmbundle/spec/gfm-spec.coffee b/src/packages/gfm.tmbundle/spec/gfm-spec.coffee
index 1ff79e62f..affdde95b 100644
--- a/src/packages/gfm.tmbundle/spec/gfm-spec.coffee
+++ b/src/packages/gfm.tmbundle/spec/gfm-spec.coffee
@@ -18,36 +18,52 @@ describe "GitHub Flavored Markdown grammar", ->
     expect(tokens[0]).toEqual value: "****", scopes: ["source.gfm"]
 
     {tokens} = grammar.tokenizeLine("this is **bold** text")
-    expect(tokens[0]).toEqual value: "this is ", scopes: ["source.gfm"]
-    expect(tokens[1]).toEqual value: "**bold**", scopes: ["source.gfm", "markup.bold.gfm"]
-    expect(tokens[2]).toEqual value: " text", scopes: ["source.gfm"]
+    expect(tokens[0]).toEqual value: "this is", scopes: ["source.gfm"]
+    expect(tokens[1]).toEqual value: " ", scopes: ["source.gfm"]
+    expect(tokens[2]).toEqual value: "**bold**", scopes: ["source.gfm", "markup.bold.gfm"]
+    expect(tokens[3]).toEqual value: " text", scopes: ["source.gfm"]
+
+    {tokens} = grammar.tokenizeLine("not**bold**")
+    expect(tokens[0]).toEqual value: "not**bold**", scopes: ["source.gfm"]
 
   it "tokenizes __bold__ text", ->
     {tokens} = grammar.tokenizeLine("____")
     expect(tokens[0]).toEqual value: "____", scopes: ["source.gfm"]
 
     {tokens} = grammar.tokenizeLine("this is __bold__ text")
-    expect(tokens[0]).toEqual value: "this is ", scopes: ["source.gfm"]
-    expect(tokens[1]).toEqual value: "__bold__", scopes: ["source.gfm", "markup.bold.gfm"]
-    expect(tokens[2]).toEqual value: " text", scopes: ["source.gfm"]
+    expect(tokens[0]).toEqual value: "this is", scopes: ["source.gfm"]
+    expect(tokens[1]).toEqual value: " ", scopes: ["source.gfm"]
+    expect(tokens[2]).toEqual value: "__bold__", scopes: ["source.gfm", "markup.bold.gfm"]
+    expect(tokens[3]).toEqual value: " text", scopes: ["source.gfm"]
+
+    {tokens} = grammar.tokenizeLine("not__bold__")
+    expect(tokens[0]).toEqual value: "not__bold__", scopes: ["source.gfm"]
 
   it "tokenizes *italic* text", ->
     {tokens} = grammar.tokenizeLine("**")
     expect(tokens[0]).toEqual value: "**", scopes: ["source.gfm"]
 
     {tokens} = grammar.tokenizeLine("this is *italic* text")
-    expect(tokens[0]).toEqual value: "this is ", scopes: ["source.gfm"]
-    expect(tokens[1]).toEqual value: "*italic*", scopes: ["source.gfm", "markup.italic.gfm"]
-    expect(tokens[2]).toEqual value: " text", scopes: ["source.gfm"]
+    expect(tokens[0]).toEqual value: "this is", scopes: ["source.gfm"]
+    expect(tokens[1]).toEqual value: " ", scopes: ["source.gfm"]
+    expect(tokens[2]).toEqual value: "*italic*", scopes: ["source.gfm", "markup.italic.gfm"]
+    expect(tokens[3]).toEqual value: " text", scopes: ["source.gfm"]
+
+    {tokens} = grammar.tokenizeLine("not*italic*")
+    expect(tokens[0]).toEqual value: "not*italic*", scopes: ["source.gfm"]
 
   it "tokenizes _italic_ text", ->
     {tokens} = grammar.tokenizeLine("__")
     expect(tokens[0]).toEqual value: "__", scopes: ["source.gfm"]
 
     {tokens} = grammar.tokenizeLine("this is _italic_ text")
-    expect(tokens[0]).toEqual value: "this is ", scopes: ["source.gfm"]
-    expect(tokens[1]).toEqual value: "_italic_", scopes: ["source.gfm", "markup.italic.gfm"]
-    expect(tokens[2]).toEqual value: " text", scopes: ["source.gfm"]
+    expect(tokens[0]).toEqual value: "this is", scopes: ["source.gfm"]
+    expect(tokens[1]).toEqual value: " ", scopes: ["source.gfm"]
+    expect(tokens[2]).toEqual value: "_italic_", scopes: ["source.gfm", "markup.italic.gfm"]
+    expect(tokens[3]).toEqual value: " text", scopes: ["source.gfm"]
+
+    {tokens} = grammar.tokenizeLine("not_italic_")
+    expect(tokens[0]).toEqual value: "not_italic_", scopes: ["source.gfm"]
 
   it "tokenizes a ## Heading", ->
     {tokens} = grammar.tokenizeLine("# Heading 1")