diff --git a/zimpl/CMakeLists.txt b/zimpl/CMakeLists.txt
index 7cf9d85..07fa187 100644
--- a/zimpl/CMakeLists.txt
+++ b/zimpl/CMakeLists.txt
@@ -151,6 +151,8 @@ include(CheckSymbolExists)
 find_library(libm m)
 if(NOT libm)
   set(libm "")
+else()
+  set(libm m)
 endif()
 
 set(libs ${libs} ${libm})