diff --git a/demo/build.bat b/demo/build.bat
index 04875d1..0666ec2 100644
--- a/demo/build.bat
+++ b/demo/build.bat
@@ -36,6 +36,7 @@ if errorlevel 1 exit /b 1
     "%ROOT_DIR%\src\ikv.c" ^
     "%ROOT_DIR%\src\loaders\ikv1.c" ^
     "%ROOT_DIR%\src\loaders\ikv2.c" ^
+    -lm ^
     -o "%TEST_EXE%"
 if errorlevel 1 exit /b 1
 goto :after_build
diff --git a/demo/build.sh b/demo/build.sh
index ad24609..72c381b 100644
--- a/demo/build.sh
+++ b/demo/build.sh
@@ -26,6 +26,7 @@ cc -std=c11 -Wall -Wextra -pedantic \
     "$ROOT_DIR/src/ikv.c" \
     "$ROOT_DIR/src/loaders/ikv1.c" \
     "$ROOT_DIR/src/loaders/ikv2.c" \
+    -lm \
     -o "$TEST_EXE"
 
 printf 'built "%s"\n' "$DEMO_EXE"
@@ -46,6 +47,7 @@ if [ "${1-}" = "coverage" ]; then
         "$ROOT_DIR/src/ikv.c" \
         "$ROOT_DIR/src/loaders/ikv1.c" \
         "$ROOT_DIR/src/loaders/ikv2.c" \
+        -lm \
         -o "$COV_EXE"
 
     (