--- spack-src/source/CMakeLists.txt
+++ spack-src/source/CMakeLists.txt
@@ -45,24 +45,24 @@
 #
 ROOT_GENERATE_DICTIONARY(
   ${library_name}_dict
-  ${CMAKE_CURRENT_SOURCE_DIR}/include/TGeoMCBranchArrayContainer.h
-  ${CMAKE_CURRENT_SOURCE_DIR}/include/TGeoMCGeometry.h
-  ${CMAKE_CURRENT_SOURCE_DIR}/include/TMCAutoLock.h
-  ${CMAKE_CURRENT_SOURCE_DIR}/include/TMCManager.h
-  ${CMAKE_CURRENT_SOURCE_DIR}/include/TMCManagerStack.h
-  ${CMAKE_CURRENT_SOURCE_DIR}/include/TMCOptical.h
-  ${CMAKE_CURRENT_SOURCE_DIR}/include/TMCParticleStatus.h
-  ${CMAKE_CURRENT_SOURCE_DIR}/include/TMCParticleType.h
-  ${CMAKE_CURRENT_SOURCE_DIR}/include/TMCProcess.h
-  ${CMAKE_CURRENT_SOURCE_DIR}/include/TMCVerbose.h
-  ${CMAKE_CURRENT_SOURCE_DIR}/include/TMCtls.h
-  ${CMAKE_CURRENT_SOURCE_DIR}/include/TVirtualMC.h
-  ${CMAKE_CURRENT_SOURCE_DIR}/include/TVirtualMCApplication.h
-  ${CMAKE_CURRENT_SOURCE_DIR}/include/TVirtualMCGeometry.h
-  ${CMAKE_CURRENT_SOURCE_DIR}/include/TVirtualMCSensitiveDetector.h
-  ${CMAKE_CURRENT_SOURCE_DIR}/include/TVirtualMCStack.h
+  TGeoMCBranchArrayContainer.h
+  TGeoMCGeometry.h
+  TMCAutoLock.h
+  TMCManager.h
+  TMCManagerStack.h
+  TMCOptical.h
+  TMCParticleStatus.h
+  TMCParticleType.h
+  TMCProcess.h
+  TMCVerbose.h
+  TMCtls.h
+  TVirtualMC.h
+  TVirtualMCApplication.h
+  TVirtualMCGeometry.h
+  TVirtualMCSensitiveDetector.h
+  TVirtualMCStack.h
   MODULE ${library_name}
-  LINKDEF ${CMAKE_CURRENT_SOURCE_DIR}/include/LinkDef.h)
+  LINKDEF include/LinkDef.h)
 
 # Files produced by the dictionary generation
 SET(root_dict
--- spack-src/source/CMakeLists.txt
+++ spack-src/source/CMakeLists.txt
@@ -63,6 +63,9 @@
   TVirtualMCSensitiveDetector.h
   TVirtualMCStack.h
   MODULE ${library_name}
+  OPTIONS "-I${CMAKE_INSTALL_PREFIX}/include/${base_name}"
+    -excludePath "${CMAKE_CURRENT_BINARY_DIR}"
+    -excludePath "${PROJECT_SOURCE_DIR}/source"
   LINKDEF include/LinkDef.h)
 
 # Files produced by the dictionary generation