diff --git a/dqclibs/libs/CMakeLists.txt b/dqclibs/libs/CMakeLists.txt
index e28ce61..4523f74 100644
--- a/dqclibs/libs/CMakeLists.txt
+++ b/dqclibs/libs/CMakeLists.txt
@@ -107,6 +107,19 @@ elseif (APPLE)
   set(CMAKE_SKIP_BUILD_RPATH  True)
   set(CMAKE_BUILD_WITH_INSTALL_RPATH ON)
   set(CMAKE_INSTALL_RPATH "@loader_path")
+  # Stamp each library's install name as @loader_path/<name>.dylib rather than
+  # the @rpath/<name>.dylib that CMAKE_MACOSX_RPATH gives by default.
+  #
+  # With an @rpath install name, dyld satisfies a dependency from ANY already
+  # loaded image whose install name matches -- it does not consult this
+  # target's LC_RPATH first. pyscf ships libcgto/libnp_helper/libcvhf/libpbc
+  # with exactly these names, so importing pyscf and dqclibs into one process
+  # cross-links the two stacks according to import order. Observed: a dlopen
+  # failure one way (missing _GTO_aopair_lazy_contract), and the other way a
+  # SIGSEGV in the FT lattice-sum driver plus PBC integrals silently returning
+  # wrong numbers. pyscf itself is immune precisely because it uses
+  # @loader_path here.
+  set(CMAKE_INSTALL_NAME_DIR "@loader_path")
 else ()
   set(CMAKE_SKIP_BUILD_RPATH  True)
   set(CMAKE_BUILD_WITH_INSTALL_RPATH True)
diff --git a/dqclibs/libs/libcint/CMakeLists.txt b/dqclibs/libs/libcint/CMakeLists.txt
index e7f6ba3..cc307a7 100644
--- a/dqclibs/libs/libcint/CMakeLists.txt
+++ b/dqclibs/libs/libcint/CMakeLists.txt
@@ -146,6 +146,28 @@ set_target_properties(cint PROPERTIES
   SOVERSION ${cint_SOVERSION}
   # LIBRARY_OUTPUT_DIRECTORY ${PROJECT_BINARY_DIR}
 )
+if (APPLE)
+  # Stamp the install name as @loader_path/libcint.<so>.dylib.
+  #
+  # WHY POST_BUILD and not INSTALL_NAME_DIR: this target is built through
+  # ExternalProject_Add straight into CMAKE_LIBRARY_OUTPUT_DIRECTORY, with no
+  # install() step that would re-stamp it, so INSTALL_NAME_DIR never applies.
+  # Setting MACOSX_RPATH OFF instead makes cmake fall back to the absolute
+  # build-tree path, which is worse than the @rpath it replaces. Rewriting the
+  # id after the link is the only form that survives both.
+  #
+  # It matters because every other dqclibs library links this one, and pyscf
+  # ships identically-named libraries: an @rpath id lets dyld satisfy the
+  # dependency from whichever image loaded first, which silently corrupts PBC
+  # integrals. libcint.dylib / libcint.4.dylib / libcint.4.0.7.dylib also all
+  # share this single id, so they collide with each other too.
+  add_custom_command(TARGET cint POST_BUILD
+    COMMAND install_name_tool -id
+            "@loader_path/libcint.${cint_SOVERSION}.dylib" $<TARGET_FILE:cint>
+    COMMAND codesign -f -s - $<TARGET_FILE:cint> || true
+    VERBATIM)
+endif ()
+
 target_link_libraries(cint ${BLAS_LIBRARIES})
 if(QUADMATH_FOUND)
   target_link_libraries(cint quadmath)