diff --git a/packages/fpmkunit/src/fpmkunit.pp b/packages/fpmkunit/src/fpmkunit.pp
index 679d33cadd..79bf36cb2b 100644
--- a/packages/fpmkunit/src/fpmkunit.pp
+++ b/packages/fpmkunit/src/fpmkunit.pp
@@ -1682,7 +1682,8 @@ ResourceString
   SInfoDestDoesNotExist   = 'Destination file "%s" does not exist.';
   SInfoFallbackBuildmode  = 'Buildmode not supported by package, falling back to one by one unit compilation';
   SInfoFallbackBuildmodeBU= 'Buildmode not supported by package, falling back to compilation using a buildunit';
-  SInfoDirectoryNoPackage = 'Found directory "%s" which does not contain a package';
+  SInfoDirectoryNoPackage = 'Found directory "%s" while searching for package "%s" which does not contain a package';
+  SInfoSrcDirectoryNoPkg  = 'Found source-directory "%s" while searching for package "%s" but the package is not compiled or has the wrong name';
 
   SDbgComparingFileTimes    = 'Comparing file "%s" time "%s" to "%s" time "%s".';
   SDbgCompilingDependenciesOfTarget = 'Compiling dependencies of target %s';
@@ -2811,7 +2812,7 @@ begin
       AnUnitConfigFilename:=APackage.Dictionary.ReplaceStrings(AnUnitConfigFilename);
       if ABuildEngine.SysFileExists(AnUnitConfigFilename) then
         APackage.UnitConfigFileName:=AnUnitConfigFilename
-      else if not IsPackageSourceLocation then
+      else
         begin
           // To avoid that directories which do not contain installed packages
           // check that there is an unit-configfile, or Packages.fpc file. (The
@@ -2820,8 +2821,22 @@ begin
           // Lazarus-source-repositories.
           if not ABuildEngine.SysFileExists(ConcatPaths([PackageBaseDir, 'Package.fpc'])) then
             begin
-              Installer.Log(vlInfo,Format(SInfoDirectoryNoPackage,[PackageBaseDir]));
-              Exit;
+              if IsPackageSourceLocation then
+                begin
+                // There is no way that I know of to confirm that a directory
+                // contains the compiled sources of the rtl. So we need a
+                // workaround. This test is skipped in case of the rtl.
+                if APackage.Name<>'rtl' then
+                  begin
+                  Installer.Log(vlInfo,Format(SInfoSrcDirectoryNoPkg,[PackageBaseDir, APackage.Name]));
+                  Exit;
+                  end;
+                end
+              else
+                begin
+                Installer.Log(vlInfo,Format(SInfoDirectoryNoPackage,[PackageBaseDir, APackage.Name]));
+                Exit;
+                end;
             end;
         end;
 
diff --git a/packages/fppkg/tests/fullfpcinstallationtests.pas b/packages/fppkg/tests/fullfpcinstallationtests.pas
index e5349f1ef0..a63e00a1ac 100644
--- a/packages/fppkg/tests/fullfpcinstallationtests.pas
+++ b/packages/fppkg/tests/fullfpcinstallationtests.pas
@@ -462,6 +462,8 @@ begin
 end;
 
 procedure TFullFPCInstallationTests.TestSourceDependency;
+var
+  s: String;
 begin
   // This is to test if fpmkunit works correctly when a dependency is available
   // not as an installed but as a (compiled) source-package. This happens for
@@ -475,6 +477,17 @@ begin
 
   RunFppkgIndir(TFullFPCInstallationSetup.GetCurrentTestBasePackagesPath + 'packageb', ['build'], 'create fpmake-executable', 1);
   RunFPMakeIndir(ConcatPaths([TFullFPCInstallationSetup.GetCurrentTestBasePackagesPath,'packageb']), ['build'], 'build packageb');
+
+  // When there is no .fpm file, fpmake should complain that the package is not
+  // compiled. (Another possibility is that another packages is mistakenly being
+  // used, for example when the package-name does not match the directory-name)
+  // This has to be enforced because without the .fpm, the dependencies are
+  // not handled.
+  s := ConcatPaths([TFullFPCInstallationSetup.GetCurrentTestBasePackagesPath,'packagea','packagea-'+TFullFPCInstallationSetup.GetTargetString+'.fpm']);
+  DeleteFile(ConcatPaths([TFullFPCInstallationSetup.GetCurrentTestBasePackagesPath,'packagea','packagea-'+TFullFPCInstallationSetup.GetTargetString+'.fpm']));
+  s := RunFPMakeIndir(ConcatPaths([TFullFPCInstallationSetup.GetCurrentTestBasePackagesPath,'packageb']), ['build', '-d'], 'build packageb without fpm', 1);
+  Check(pos('the package is not compiled', s) > 0, 'Missing .fpm-file detection did not trigger');
+  Check(pos('Could not find unit directory for dependency package', s) > 0, 'Incorrect error message');
 end;
 
 procedure TFullFPCInstallationTests.TestTransmitOptions;