diff --git a/src/core/qgscoordinatereferencesystem.cpp b/src/core/qgscoordinatereferencesystem.cpp
index 5727622d8b3..07c43155d0e 100644
--- a/src/core/qgscoordinatereferencesystem.cpp
+++ b/src/core/qgscoordinatereferencesystem.cpp
@@ -28,6 +28,7 @@
 #include <QRegExp>
 #include <QTextStream>
 #include <QFile>
+#include <QRegularExpression>
 
 #include "qgsapplication.h"
 #include "qgslogger.h"
@@ -220,26 +221,28 @@ bool QgsCoordinateReferenceSystem::createFromString( const QString &definition )
   sCrsStringLock.unlock();
 
   bool result = false;
-  QRegExp reCrsId( "^(epsg|postgis|internal)\\:(\\d+)$", Qt::CaseInsensitive );
-  if ( reCrsId.indexIn( definition ) == 0 )
+  QRegularExpression reCrsId( "^(epsg|postgis|internal|user)\\:(\\d+)$", QRegularExpression::CaseInsensitiveOption );
+  QRegularExpressionMatch match = reCrsId.match( definition );
+  if ( match.capturedStart() == 0 )
   {
-    QString authName = reCrsId.cap( 1 ).toLower();
+    QString authName = match.captured( 1 ).toLower();
     CrsType type = InternalCrsId;
     if ( authName == QLatin1String( "epsg" ) )
       type = EpsgCrsId;
     if ( authName == QLatin1String( "postgis" ) )
       type = PostgisCrsId;
-    long id = reCrsId.cap( 2 ).toLong();
+    long id = match.captured( 2 ).toLong();
     result = createFromId( id, type );
   }
   else
   {
-    QRegExp reCrsStr( "^(?:(wkt|proj4)\\:)?(.+)$", Qt::CaseInsensitive );
-    if ( reCrsStr.indexIn( definition ) == 0 )
+    QRegularExpression reCrsStr( "^(?:(wkt|proj4)\\:)?(.+)$", QRegularExpression::CaseInsensitiveOption );
+    match = reCrsStr.match( definition );
+    if ( match.capturedStart() == 0 )
     {
-      if ( reCrsStr.cap( 1 ).toLower() == QLatin1String( "proj4" ) )
+      if ( match.captured( 1 ).toLower() == QLatin1String( "proj4" ) )
       {
-        result = createFromProj4( reCrsStr.cap( 2 ) );
+        result = createFromProj4( match.captured( 2 ) );
         //TODO: createFromProj4 used to save to the user database any new CRS
         // this behavior was changed in order to separate creation and saving.
         // Not sure if it necessary to save it here, should be checked by someone
@@ -254,7 +257,7 @@ bool QgsCoordinateReferenceSystem::createFromString( const QString &definition )
       }
       else
       {
-        result = createFromWkt( reCrsStr.cap( 2 ) );
+        result = createFromWkt( match.captured( 2 ) );
       }
     }
   }
diff --git a/tests/src/core/testqgscoordinatereferencesystem.cpp b/tests/src/core/testqgscoordinatereferencesystem.cpp
index bc00efa844e..ceea0a67d48 100644
--- a/tests/src/core/testqgscoordinatereferencesystem.cpp
+++ b/tests/src/core/testqgscoordinatereferencesystem.cpp
@@ -842,6 +842,14 @@ void TestQgsCoordinateReferenceSystem::saveAsUserCrs()
   QCOMPARE( userCrs2.srsid(), userCrs.srsid() );
   QCOMPARE( userCrs2.authid(), QStringLiteral( "USER:100000" ) );
   QCOMPARE( userCrs2.description(), QStringLiteral( "babies first projection" ) );
+
+  // createFromString with user crs
+  QgsCoordinateReferenceSystem userCrs3;
+  userCrs3.createFromString( QStringLiteral( "USER:100000" ) );
+  QVERIFY( userCrs3.isValid() );
+  QCOMPARE( userCrs3.authid(), QString( "USER:100000" ) );
+  QCOMPARE( userCrs3.toProj4(), madeUpProjection );
+  QCOMPARE( userCrs3.description(), QStringLiteral( "babies first projection" ) );
 }
 
 void TestQgsCoordinateReferenceSystem::projectWithCustomCrs()