diff --git a/netwerk/mime/nsMIMEHeaderParamImpl.cpp b/netwerk/mime/nsMIMEHeaderParamImpl.cpp
index f25baa5c5036..b799d2ed88db 100644
--- a/netwerk/mime/nsMIMEHeaderParamImpl.cpp
+++ b/netwerk/mime/nsMIMEHeaderParamImpl.cpp
@@ -1157,7 +1157,7 @@ nsresult DecodeQOrBase64Str(const char *aEncoded, size_t aLen, char aQOrBase64,
   return NS_OK;
 }
 
-static const char especials[] = "()<>@,;:\\\"/[]?.=";
+static const char especials[] = R"(()<>@,;:\"/[]?.=)";
 
 // |decode_mime_part2_str| taken from comi18n.c
 // Decode RFC2047-encoded words in the input and convert the result to UTF-8.
diff --git a/netwerk/protocol/http/nsHttpHandler.cpp b/netwerk/protocol/http/nsHttpHandler.cpp
index 503f9a7b93de..70c2a77d3330 100644
--- a/netwerk/protocol/http/nsHttpHandler.cpp
+++ b/netwerk/protocol/http/nsHttpHandler.cpp
@@ -331,7 +331,7 @@ nsHttpHandler::Init()
           appInfo->GetName(mAppName);
         }
         appInfo->GetVersion(mAppVersion);
-        mAppName.StripChars(" ()<>@,;:\\\"/[]?={}");
+        mAppName.StripChars(R"( ()<>@,;:\"/[]?={})");
     } else {
         mAppVersion.AssignLiteral(MOZ_APP_UA_VERSION);
     }
diff --git a/netwerk/test/TestCookie.cpp b/netwerk/test/TestCookie.cpp
index f1b259c2c985..ee3393cc4271 100644
--- a/netwerk/test/TestCookie.cpp
+++ b/netwerk/test/TestCookie.cpp
@@ -71,7 +71,7 @@ SetACookie(nsICookieService *aCookieService, const char *aSpec1, const char *aSp
     if (aSpec2)
         NS_NewURI(getter_AddRefs(uri2), aSpec2);
 
-    sBuffer = PR_sprintf_append(sBuffer, "    for host \"%s\": SET ", aSpec1);
+    sBuffer = PR_sprintf_append(sBuffer, R"(    for host "%s": SET )", aSpec1);
     nsresult rv = aCookieService->SetCookieStringFromHttp(uri1, uri2, nullptr, (char *)aCookieString, aServerTime, nullptr);
     // the following code is useless. the cookieservice blindly returns NS_OK
     // from SetCookieString. we have to call GetCookie to see if the cookie was
@@ -90,7 +90,7 @@ SetACookieNoHttp(nsICookieService *aCookieService, const char *aSpec, const char
     nsCOMPtr<nsIURI> uri;
     NS_NewURI(getter_AddRefs(uri), aSpec);
 
-    sBuffer = PR_sprintf_append(sBuffer, "    for host \"%s\": SET ", aSpec);
+    sBuffer = PR_sprintf_append(sBuffer, R"(    for host "%s": SET )", aSpec);
     nsresult rv = aCookieService->SetCookieString(uri, nullptr, (char *)aCookieString, nullptr);
     // the following code is useless. the cookieservice blindly returns NS_OK
     // from SetCookieString. we have to call GetCookie to see if the cookie was
@@ -113,7 +113,7 @@ GetACookie(nsICookieService *aCookieService, const char *aSpec1, const char *aSp
     if (aSpec2)
         NS_NewURI(getter_AddRefs(uri2), aSpec2);
 
-    sBuffer = PR_sprintf_append(sBuffer, "             \"%s\": GOT ", aSpec1);
+    sBuffer = PR_sprintf_append(sBuffer, R"(             "%s": GOT )", aSpec1);
     nsresult rv = aCookieService->GetCookieStringFromHttp(uri1, uri2, nullptr, aCookie);
     if (NS_FAILED(rv)) {
       sBuffer = PR_sprintf_append(sBuffer, "XXX GetCookieString() failed!\n");
@@ -134,7 +134,7 @@ GetACookieNoHttp(nsICookieService *aCookieService, const char *aSpec, char **aCo
     nsCOMPtr<nsIURI> uri;
     NS_NewURI(getter_AddRefs(uri), aSpec);
 
-    sBuffer = PR_sprintf_append(sBuffer, "             \"%s\": GOT ", aSpec);
+    sBuffer = PR_sprintf_append(sBuffer, R"(             "%s": GOT )", aSpec);
     nsresult rv = aCookieService->GetCookieString(uri, nullptr, aCookie);
     if (NS_FAILED(rv)) {
       sBuffer = PR_sprintf_append(sBuffer, "XXX GetCookieString() failed!\n");
@@ -355,7 +355,7 @@ main(int32_t argc, char *argv[])
       GetACookie(cookieService, "http://foo.domain.com", nullptr, getter_Copies(cookie));
       rv[13] = CheckResult(cookie.get(), MUST_BE_NULL);
 
-      SetACookie(cookieService, "http://path.net/path/file", nullptr, "test=taco; path=\"/bogus\"", nullptr);
+      SetACookie(cookieService, "http://path.net/path/file", nullptr, R"(test=taco; path="/bogus")", nullptr);
       GetACookie(cookieService, "http://path.net/path/file", nullptr, getter_Copies(cookie));
       rv[14] = CheckResult(cookie.get(), MUST_EQUAL, "test=taco");
       SetACookie(cookieService, "http://path.net/path/file", nullptr, "test=taco; max-age=-1", nullptr);
@@ -455,10 +455,10 @@ main(int32_t argc, char *argv[])
       SetACookie(cookieService, "http://expireme.org/", nullptr, "test=expiry; expires=Thu, 10 Apr 1980 16:33:12 GMT", nullptr);
       GetACookie(cookieService, "http://expireme.org/", nullptr, getter_Copies(cookie));
       rv[3] = CheckResult(cookie.get(), MUST_BE_NULL);
-      SetACookie(cookieService, "http://expireme.org/", nullptr, "test=expiry; expires=\"Thu, 10 Apr 1980 16:33:12 GMT", nullptr);
+      SetACookie(cookieService, "http://expireme.org/", nullptr, R"(test=expiry; expires="Thu, 10 Apr 1980 16:33:12 GMT)", nullptr);
       GetACookie(cookieService, "http://expireme.org/", nullptr, getter_Copies(cookie));
       rv[4] = CheckResult(cookie.get(), MUST_BE_NULL);
-      SetACookie(cookieService, "http://expireme.org/", nullptr, "test=expiry; expires=\"Thu, 10 Apr 1980 16:33:12 GMT\"", nullptr);
+      SetACookie(cookieService, "http://expireme.org/", nullptr, R"(test=expiry; expires="Thu, 10 Apr 1980 16:33:12 GMT")", nullptr);
       GetACookie(cookieService, "http://expireme.org/", nullptr, getter_Copies(cookie));
       rv[5] = CheckResult(cookie.get(), MUST_BE_NULL);
 
@@ -555,7 +555,7 @@ main(int32_t argc, char *argv[])
       rv[1] = CheckResult(cookie.get(), MUST_BE_NULL);
       SetACookie(cookieService, "http://parser.test/", nullptr, "test=\"fubar! = foo;bar\\\";\" parser; domain=.parser.test; max-age=6\nfive; max-age=2.63,", nullptr);
       GetACookie(cookieService, "http://parser.test/", nullptr, getter_Copies(cookie));
-      rv[2] = CheckResult(cookie.get(), MUST_CONTAIN, "test=\"fubar! = foo");
+      rv[2] = CheckResult(cookie.get(), MUST_CONTAIN, R"(test="fubar! = foo)");
       rv[3] = CheckResult(cookie.get(), MUST_CONTAIN, "five");
       SetACookie(cookieService, "http://parser.test/", nullptr, "test=kill; domain=.parser.test; max-age=0 \n five; max-age=0", nullptr);
       GetACookie(cookieService, "http://parser.test/", nullptr, getter_Copies(cookie));
diff --git a/netwerk/test/TestProtocols.cpp b/netwerk/test/TestProtocols.cpp
index f6126551097e..7bec14f856d2 100644
--- a/netwerk/test/TestProtocols.cpp
+++ b/netwerk/test/TestProtocols.cpp
@@ -799,7 +799,7 @@ nsresult LoadURLsFromFile(char *aFileName)
 nsresult LoadURLFromConsole()
 {
     char buffer[1024];
-    printf("Enter URL (\"q\" to start): ");
+    printf(R"(Enter URL ("q" to start): )");
     Unused << scanf("%s", buffer);
     if (buffer[0]=='q') 
         gAskUserForInput = false;
diff --git a/netwerk/test/urltest.cpp b/netwerk/test/urltest.cpp
index eaef3472c476..df6f3f301fe6 100644
--- a/netwerk/test/urltest.cpp
+++ b/netwerk/test/urltest.cpp
@@ -339,7 +339,7 @@ nsresult doMakeAbsTest(const char* i_URL = 0, const char* i_relativePortion=0)
         { "http://a/b/c/d;p?q#f",     "g/h/../H?http://foo#bar", "http://a/b/c/g/H?http://foo#bar" },
         { "http://a/b/c/d;p?q#f",     "g/h/../H;baz?http://foo", "http://a/b/c/g/H;baz?http://foo" },
         { "http://a/b/c/d;p?q#f",     "g/h/../H;baz?http://foo#bar", "http://a/b/c/g/H;baz?http://foo#bar" },
-        { "http://a/b/c/d;p?q#f",     "g/h/../H;baz?C:\\temp", "http://a/b/c/g/H;baz?C:\\temp" },
+        { "http://a/b/c/d;p?q#f",     R"(g/h/../H;baz?C:\temp)", R"(http://a/b/c/g/H;baz?C:\temp)" },
         { "http://a/b/c/d;p?q#f",     "", "http://a/b/c/d;p?q" },
         { "http://a/b/c/d;p?q#f",     "#", "http://a/b/c/d;p?q#" },
         { "http://a/b/c;p/d;p?q#f",   "../g;p" , "http://a/b/g;p" },