diff --git a/app/models/repository.rb b/app/models/repository.rb
index 2ffd9558ebc..66869d0539b 100644
--- a/app/models/repository.rb
+++ b/app/models/repository.rb
@@ -932,7 +932,7 @@ class Repository
     return [] if empty? || query.blank?
 
     offset = 2
-    args = %W(grep -i -I -n --before-context #{offset} --after-context #{offset} -E -e #{Regexp.escape(query)} #{ref || root_ref})
+    args = %W(grep -i -I -n -z --before-context #{offset} --after-context #{offset} -E -e #{Regexp.escape(query)} #{ref || root_ref})
 
     run_git(args).first.scrub.split(/^--$/)
   end
diff --git a/changelogs/unreleased/41666-cannot-search-with-keyword-merge.yml b/changelogs/unreleased/41666-cannot-search-with-keyword-merge.yml
new file mode 100644
index 00000000000..3a6fa425c9c
--- /dev/null
+++ b/changelogs/unreleased/41666-cannot-search-with-keyword-merge.yml
@@ -0,0 +1,6 @@
+---
+title: Fix file search results when they match file contents with a number between
+  two colons
+merge_request: 16462
+author:
+type: fixed
diff --git a/lib/gitlab/project_search_results.rb b/lib/gitlab/project_search_results.rb
index e2662fc362b..7771b15069b 100644
--- a/lib/gitlab/project_search_results.rb
+++ b/lib/gitlab/project_search_results.rb
@@ -44,25 +44,20 @@ module Gitlab
       ref = nil
       filename = nil
       basename = nil
+      data = ""
       startline = 0
 
-      result.each_line.each_with_index do |line, index|
-        matches = line.match(/^(?<ref>[^:]*):(?<filename>.*):(?<startline>\d+):/)
-        if matches
+      result.strip.each_line.each_with_index do |line, index|
+        prefix ||= line.match(/^(?<ref>[^:]*):(?<filename>.*)\x00(?<startline>\d+)\x00/)&.tap do |matches|
           ref = matches[:ref]
           filename = matches[:filename]
           startline = matches[:startline]
           startline = startline.to_i - index
           extname = Regexp.escape(File.extname(filename))
           basename = filename.sub(/#{extname}$/, '')
-          break
         end
-      end
 
-      data = ""
-
-      result.each_line do |line|
-        data << line.sub(ref, '').sub(filename, '').sub(/^:-\d+-/, '').sub(/^::\d+:/, '')
+        data << line.sub(prefix.to_s, '')
       end
 
       FoundBlob.new(
diff --git a/spec/lib/gitlab/project_search_results_spec.rb b/spec/lib/gitlab/project_search_results_spec.rb
index 17937726f2c..1ebb0105cf5 100644
--- a/spec/lib/gitlab/project_search_results_spec.rb
+++ b/spec/lib/gitlab/project_search_results_spec.rb
@@ -70,15 +70,6 @@ describe Gitlab::ProjectSearchResults do
 
       subject { described_class.parse_search_result(search_result) }
 
-      it 'can correctly parse filenames including ":"' do
-        special_char_result = "\nmaster:testdata/project::function1.yaml-1----\nmaster:testdata/project::function1.yaml:2:test: data1\n"
-
-        blob = described_class.parse_search_result(special_char_result)
-
-        expect(blob.ref).to eq('master')
-        expect(blob.filename).to eq('testdata/project::function1.yaml')
-      end
-
       it "returns a valid FoundBlob" do
         is_expected.to be_an Gitlab::SearchResults::FoundBlob
         expect(subject.id).to be_nil
@@ -90,8 +81,32 @@ describe Gitlab::ProjectSearchResults do
         expect(subject.data.lines[2]).to eq("  - Feature: Replace teams with group membership\n")
       end
 
+      context 'when the matching filename contains a colon' do
+        let(:search_result) { "\nmaster:testdata/project::function1.yaml\x001\x00---\n" }
+
+        it 'returns a valid FoundBlob' do
+          expect(subject.filename).to eq('testdata/project::function1.yaml')
+          expect(subject.basename).to eq('testdata/project::function1')
+          expect(subject.ref).to eq('master')
+          expect(subject.startline).to eq(1)
+          expect(subject.data).to eq('---')
+        end
+      end
+
+      context 'when the matching content contains a number surrounded by colons' do
+        let(:search_result) { "\nmaster:testdata/foo.txt\x001\x00blah:9:blah" }
+
+        it 'returns a valid FoundBlob' do
+          expect(subject.filename).to eq('testdata/foo.txt')
+          expect(subject.basename).to eq('testdata/foo')
+          expect(subject.ref).to eq('master')
+          expect(subject.startline).to eq(1)
+          expect(subject.data).to eq('blah:9:blah')
+        end
+      end
+
       context "when filename has extension" do
-        let(:search_result) { "master:CONTRIBUTE.md:5:- [Contribute to GitLab](#contribute-to-gitlab)\n" }
+        let(:search_result) { "master:CONTRIBUTE.md\x005\x00- [Contribute to GitLab](#contribute-to-gitlab)\n" }
 
         it { expect(subject.path).to eq('CONTRIBUTE.md') }
         it { expect(subject.filename).to eq('CONTRIBUTE.md') }
@@ -99,7 +114,7 @@ describe Gitlab::ProjectSearchResults do
       end
 
       context "when file under directory" do
-        let(:search_result) { "master:a/b/c.md:5:a b c\n" }
+        let(:search_result) { "master:a/b/c.md\x005\x00a b c\n" }
 
         it { expect(subject.path).to eq('a/b/c.md') }
         it { expect(subject.filename).to eq('a/b/c.md') }
@@ -144,7 +159,7 @@ describe Gitlab::ProjectSearchResults do
     end
 
     it 'finds by content' do
-      expect(results).to include("master:Title.md:1:Content\n")
+      expect(results).to include("master:Title.md\x001\x00Content\n")
     end
   end
 
diff --git a/spec/models/repository_spec.rb b/spec/models/repository_spec.rb
index f3456e5b354..7e215e37de3 100644
--- a/spec/models/repository_spec.rb
+++ b/spec/models/repository_spec.rb
@@ -657,7 +657,7 @@ describe Repository do
       subject { results.first }
 
       it { is_expected.to be_an String }
-      it { expect(subject.lines[2]).to eq("master:CHANGELOG:190:  - Feature: Replace teams with group membership\n") }
+      it { expect(subject.lines[2]).to eq("master:CHANGELOG\x00190\x00  - Feature: Replace teams with group membership\n") }
     end
   end