diff --git a/public/app/plugins/datasource/loki/syntax.test.ts b/public/app/plugins/datasource/loki/syntax.test.ts
new file mode 100644
index 00000000000..7a5fcf18568
--- /dev/null
+++ b/public/app/plugins/datasource/loki/syntax.test.ts
@@ -0,0 +1,22 @@
+import syntax from './syntax';
+import Prism from 'prismjs';
+
+describe('Loki syntax', () => {
+  it('should highlight Loki query correctly', () => {
+    expect(Prism.highlight('{key="val#ue"}', syntax, 'loki')).toBe(
+      '<span class="token context-labels"><span class="token punctuation">{</span><span class="token label-key attr-name">key</span>=<span class="token label-value attr-value">"val#ue"</span></span><span class="token punctuation">}</span>'
+    );
+    expect(Prism.highlight('{key="#value"}', syntax, 'loki')).toBe(
+      '<span class="token context-labels"><span class="token punctuation">{</span><span class="token label-key attr-name">key</span>=<span class="token label-value attr-value">"#value"</span></span><span class="token punctuation">}</span>'
+    );
+    expect(Prism.highlight('{key="value#"}', syntax, 'loki')).toBe(
+      '<span class="token context-labels"><span class="token punctuation">{</span><span class="token label-key attr-name">key</span>=<span class="token label-value attr-value">"value#"</span></span><span class="token punctuation">}</span>'
+    );
+    expect(Prism.highlight('#test{key="value"}', syntax, 'loki')).toBe(
+      '<span class="token comment">#test{key="value"}</span>'
+    );
+    expect(Prism.highlight('{key="value"}#test', syntax, 'loki')).toBe(
+      '<span class="token context-labels"><span class="token punctuation">{</span><span class="token label-key attr-name">key</span>=<span class="token label-value attr-value">"value"</span></span><span class="token punctuation">}</span><span class="token comment">#test</span>'
+    );
+  });
+});
diff --git a/public/app/plugins/datasource/loki/syntax.ts b/public/app/plugins/datasource/loki/syntax.ts
index f42c337eacc..fc2406479cf 100644
--- a/public/app/plugins/datasource/loki/syntax.ts
+++ b/public/app/plugins/datasource/loki/syntax.ts
@@ -69,8 +69,7 @@ export const FUNCTIONS = [...AGGREGATION_OPERATORS, ...RANGE_VEC_FUNCTIONS];
 
 const tokenizer: Grammar = {
   comment: {
-    pattern: /(^|[^\n])#.*/,
-    lookbehind: true,
+    pattern: /#.*/,
   },
   'context-aggregation': {
     pattern: /((without|by)\s*)\([^)]*\)/, // by ()
@@ -85,11 +84,15 @@ const tokenizer: Grammar = {
   },
   'context-labels': {
     pattern: /\{[^}]*(?=})/,
-    lookbehind: true,
+    greedy: true,
     inside: {
+      comment: {
+        pattern: /#.*/,
+      },
       'label-key': {
         pattern: /[a-z_]\w*(?=\s*(=|!=|=~|!~))/,
         alias: 'attr-name',
+        greedy: true,
       },
       'label-value': {
         pattern: /"(?:\\.|[^\\"])*"/,
diff --git a/public/app/plugins/datasource/prometheus/promql.test.ts b/public/app/plugins/datasource/prometheus/promql.test.ts
new file mode 100644
index 00000000000..2b0cc20fd1e
--- /dev/null
+++ b/public/app/plugins/datasource/prometheus/promql.test.ts
@@ -0,0 +1,22 @@
+import promql from './promql';
+import Prism from 'prismjs';
+
+describe('Loki syntax', () => {
+  it('should highlight Loki query correctly', () => {
+    expect(Prism.highlight('{key="val#ue"}', promql, 'promql')).toBe(
+      '<span class="token context-labels"><span class="token punctuation">{</span><span class="token label-key attr-name">key</span>=<span class="token label-value attr-value">"val#ue"</span></span><span class="token punctuation">}</span>'
+    );
+    expect(Prism.highlight('{key="#value"}', promql, 'promql')).toBe(
+      '<span class="token context-labels"><span class="token punctuation">{</span><span class="token label-key attr-name">key</span>=<span class="token label-value attr-value">"#value"</span></span><span class="token punctuation">}</span>'
+    );
+    expect(Prism.highlight('{key="value#"}', promql, 'promql')).toBe(
+      '<span class="token context-labels"><span class="token punctuation">{</span><span class="token label-key attr-name">key</span>=<span class="token label-value attr-value">"value#"</span></span><span class="token punctuation">}</span>'
+    );
+    expect(Prism.highlight('#test{key="value"}', promql, 'promql')).toBe(
+      '<span class="token comment">#test{key="value"}</span>'
+    );
+    expect(Prism.highlight('{key="value"}#test', promql, 'promql')).toBe(
+      '<span class="token context-labels"><span class="token punctuation">{</span><span class="token label-key attr-name">key</span>=<span class="token label-value attr-value">"value"</span></span><span class="token punctuation">}</span><span class="token comment">#test</span>'
+    );
+  });
+});
diff --git a/public/app/plugins/datasource/prometheus/promql.ts b/public/app/plugins/datasource/prometheus/promql.ts
index 0bde2da9c2f..d4b68200ba6 100644
--- a/public/app/plugins/datasource/prometheus/promql.ts
+++ b/public/app/plugins/datasource/prometheus/promql.ts
@@ -377,8 +377,7 @@ export const FUNCTIONS = [
 
 const tokenizer = {
   comment: {
-    pattern: /(^|[^\n])#.*/,
-    lookbehind: true,
+    pattern: /#.*/,
   },
   'context-aggregation': {
     pattern: /((by|without)\s*)\([^)]*\)/, // by ()
@@ -393,10 +392,15 @@ const tokenizer = {
   },
   'context-labels': {
     pattern: /\{[^}]*(?=})/,
+    greedy: true,
     inside: {
+      comment: {
+        pattern: /#.*/,
+      },
       'label-key': {
         pattern: /[a-z_]\w*(?=\s*(=|!=|=~|!~))/,
         alias: 'attr-name',
+        greedy: true,
       },
       'label-value': {
         pattern: /"(?:\\.|[^\\"])*"/,