diff --git a/extern/CMakeProject-tomcrypt.cmake b/extern/CMakeProject-tomcrypt.cmake
index cced8bbe11..3c5a9cc4d0 100644
--- a/extern/CMakeProject-tomcrypt.cmake
+++ b/extern/CMakeProject-tomcrypt.cmake
@@ -1,5 +1,6 @@
 if(WITH_SYSTEM_TOMCRYPT)
-  find_library(TOMCRYPT_LIBRARY tomcrypt)
+  find_package(PkgConfig REQUIRED)
+  pkg_check_modules(TOMCRYPT REQUIRED libtomcrypt IMPORTED_TARGET GLOBAL)
 else()
   set(TOMDIR "${SM_SRC_DIR}/libtomcrypt")
 
diff --git a/extern/CMakeProject-tommath.cmake b/extern/CMakeProject-tommath.cmake
index 953b7b0b81..5a36fd3abe 100644
--- a/extern/CMakeProject-tommath.cmake
+++ b/extern/CMakeProject-tommath.cmake
@@ -1,8 +1,6 @@
 if(WITH_SYSTEM_TOMMATH)
-  find_library(TOMMATH_LIBRARY tommath)
-  if(TOMMATH_LIBRARY MATCHES "TOMMATH_LIBRARY-NOTFOUND")
-    message(FATAL_ERROR "Need tommath.")
-  endif()
+  find_package(PkgConfig REQUIRED)
+  pkg_check_modules(TOMMATH REQUIRED libtommath IMPORTED_TARGET GLOBAL)
 else()
   set(TOMDIR "${SM_SRC_DIR}/libtommath")
 
diff --git a/src/CMakeLists.txt b/src/CMakeLists.txt
index 0feb8ed722..6a9d82cae6 100644
--- a/src/CMakeLists.txt
+++ b/src/CMakeLists.txt
@@ -451,13 +457,13 @@ else()
 endif()
 
 if(WITH_SYSTEM_TOMCRYPT)
-  list(APPEND SMDATA_LINK_LIB ${TOMCRYPT_LIBRARY})
+  list(APPEND SMDATA_LINK_LIB PkgConfig::TOMCRYPT)
 else()
   list(APPEND SMDATA_LINK_LIB "tomcrypt")
 endif()
 
 if(WITH_SYSTEM_TOMMATH)
-  list(APPEND SMDATA_LINK_LIB ${TOMMATH_LIBRARY})
+  list(APPEND SMDATA_LINK_LIB PkgConfig::TOMMATH)
 else()
   list(APPEND SMDATA_LINK_LIB "tommath")
 endif()