diff --git a/cmake/finders/FindBLAS.cmake b/cmake/finders/FindBLAS.cmake
index f2f5be11d5..25d0f909f5 100644
--- a/cmake/finders/FindBLAS.cmake
+++ b/cmake/finders/FindBLAS.cmake
@@ -6,14 +6,33 @@
 cmake_policy(PUSH)
 cmake_policy(SET CMP0057 NEW)
 
-if("OpenBLAS" IN_LIST THEROCK_PROVIDED_PACKAGES)
-  cmake_policy(POP)
+if(("OpenBLAS" IN_LIST THEROCK_PROVIDED_PACKAGES) OR ("OpenBLAS64" IN_LIST
+                                                     THEROCK_PROVIDED_PACKAGES))
   message(STATUS "Resolving bundled host-blas library from super-project")
 
+  set(_want_ilp64 FALSE)
   if(DEFINED BLA_SIZEOF_INTEGER AND BLA_SIZEOF_INTEGER EQUAL 8)
+    set(_want_ilp64 TRUE)
+  endif()
+
+  if(_want_ilp64)
+    if(NOT "OpenBLAS64" IN_LIST THEROCK_PROVIDED_PACKAGES)
+      message(
+        FATAL_ERROR
+          "BLA_SIZEOF_INTEGER=8 (ILP64) requested but the super-project did not "
+          "provide OpenBLAS64. Add therock-host-blas64 to this subproject's "
+          "BUILD_DEPS or RUNTIME_DEPS.")
+    endif()
     find_package(OpenBLAS64 CONFIG REQUIRED)
     set(_OPENBLAS OpenBLAS64)
   else()
+    if(NOT "OpenBLAS" IN_LIST THEROCK_PROVIDED_PACKAGES)
+      message(
+        FATAL_ERROR
+          "LP64 BLAS requested but the super-project did not provide OpenBLAS. "
+          "Add therock-host-blas, or set BLA_SIZEOF_INTEGER=8 if only OpenBLAS64 "
+          "is available.")
+    endif()
     find_package(OpenBLAS CONFIG REQUIRED)
     set(_OPENBLAS OpenBLAS)
   endif()
@@ -25,6 +44,7 @@ if("OpenBLAS" IN_LIST THEROCK_PROVIDED_PACKAGES)
   set(BLAS95_LIBRARIES)
   set(BLAS95_FOUND FALSE)
   set(BLAS_FOUND TRUE)
+  cmake_policy(POP)
 else()
   cmake_policy(POP)
   set(BLAS_FOUND FALSE)
diff --git a/cmake/finders/FindLAPACK.cmake b/cmake/finders/FindLAPACK.cmake
index a5cfa57c28..20263aa71a 100644
--- a/cmake/finders/FindLAPACK.cmake
+++ b/cmake/finders/FindLAPACK.cmake
@@ -6,25 +6,45 @@
 cmake_policy(PUSH)
 cmake_policy(SET CMP0057 NEW)
 
-if("OpenBLAS" IN_LIST THEROCK_PROVIDED_PACKAGES)
-  cmake_policy(POP)
+if(("OpenBLAS" IN_LIST THEROCK_PROVIDED_PACKAGES) OR ("OpenBLAS64" IN_LIST
+                                                     THEROCK_PROVIDED_PACKAGES))
   message(STATUS "Resolving bundled host-blas library from super-project")
 
+  set(_want_ilp64 FALSE)
   if(DEFINED BLA_SIZEOF_INTEGER AND BLA_SIZEOF_INTEGER EQUAL 8)
+    set(_want_ilp64 TRUE)
+  endif()
+
+  if(_want_ilp64)
+    if(NOT "OpenBLAS64" IN_LIST THEROCK_PROVIDED_PACKAGES)
+      message(
+        FATAL_ERROR
+          "BLA_SIZEOF_INTEGER=8 (ILP64) requested but the super-project did not "
+          "provide OpenBLAS64. Add therock-host-blas64 to this subproject's "
+          "BUILD_DEPS or RUNTIME_DEPS.")
+    endif()
     find_package(OpenBLAS64 CONFIG REQUIRED)
     set(_OPENBLAS OpenBLAS64)
   else()
+    if(NOT "OpenBLAS" IN_LIST THEROCK_PROVIDED_PACKAGES)
+      message(
+        FATAL_ERROR
+          "LP64 LAPACK requested but the super-project did not provide OpenBLAS. "
+          "Add therock-host-blas, or set BLA_SIZEOF_INTEGER=8 if only OpenBLAS64 "
+          "is available.")
+    endif()
     find_package(OpenBLAS CONFIG REQUIRED)
     set(_OPENBLAS OpenBLAS)
   endif()
 
-  # See: https://cmake.org/cmake/help/latest/module/FindBLAS.html
+  # See: https://cmake.org/cmake/help/latest/module/FindLAPACK.html
   set(LAPACK_LINKER_FLAGS)
   set(LAPACK_LIBRARIES ${_OPENBLAS}::OpenBLAS)
   add_library(LAPACK::LAPACK ALIAS ${_OPENBLAS}::OpenBLAS)
   set(LAPACK95_LIBRARIES)
   set(LAPACK95_FOUND FALSE)
   set(LAPACK_FOUND TRUE)
+  cmake_policy(POP)
 else()
   cmake_policy(POP)
   set(LAPACK_FOUND FALSE)
diff --git a/math-libs/BLAS/CMakeLists.txt b/math-libs/BLAS/CMakeLists.txt
index 623cb8e977..14f3019c31 100644
--- a/math-libs/BLAS/CMakeLists.txt
+++ b/math-libs/BLAS/CMakeLists.txt
@@ -173,8 +173,15 @@ if(NOT WIN32)
   if(TARGET rocm_smi_lib)
     list(APPEND rocBLAS_optional_runtime_deps rocm_smi_lib)
   endif()
-elseif(THEROCK_BUILD_TESTING)
-  list(APPEND rocBLAS_optional_runtime_deps therock-host-blas)
+endif()
+if(THEROCK_BUILD_TESTING)
+  # Client tests link ILP64 reference BLAS (see cmake/finders/FindBLAS.cmake + BLA_SIZEOF_INTEGER=8).
+  list(APPEND rocBLAS_optional_runtime_deps therock-host-blas64)
+endif()
+
+set(rocBLAS_extra_cmake_args)
+if(THEROCK_BUILD_TESTING)
+  list(APPEND rocBLAS_extra_cmake_args -DROCBLAS_CLIENTS_REFERENCE_ILP64=ON)
 endif()
 
 # Disable rocBLAS samples on Windows due to use of deprecated
@@ -206,6 +213,7 @@ therock_cmake_subproject_declare(rocBLAS
     -DBUILD_CLIENTS_SAMPLES=${_blas_build_samples}
     -DBUILD_CLIENTS_BENCHMARKS=${THEROCK_BUILD_TESTING}
     -DLINK_BLIS=OFF
+    ${rocBLAS_extra_cmake_args}
   CMAKE_INCLUDES
     therock_explicit_finders.cmake
   COMPILER_TOOLCHAIN
diff --git a/rocm-libraries b/rocm-libraries
index f000f7786e..83700a79d2 160000
--- a/rocm-libraries
+++ b/rocm-libraries
@@ -1 +1 @@
-Subproject commit f000f7786e9ac67510549f4d17784d327705e295
+Subproject commit 83700a79d25b025dabb30095e4e6ec45bc05ccb1