diff --git a/build-compiler-rt.sh b/build-compiler-rt.sh
index 5439e39..e3636f9 100755
--- a/build-compiler-rt.sh
+++ b/build-compiler-rt.sh
@@ -123,7 +123,7 @@ for arch in $ARCHS; do
         -DCMAKE_C_FLAGS_INIT="$CFGUARD_CFLAGS" \
         -DCMAKE_CXX_FLAGS_INIT="$CFGUARD_CFLAGS" \
         $SRC_DIR
-    $BUILDCMD ${CORES+-j$CORES}
+    $BUILDCMD ${CORES:+-j${CORES}}
     $BUILDCMD install
     mkdir -p "$PREFIX/$arch-w64-mingw32/bin"
     if [ -n "$SANITIZERS" ]; then
diff --git a/build-libcxx.sh b/build-libcxx.sh
index 01b1dd2..67a1336 100755
--- a/build-libcxx.sh
+++ b/build-libcxx.sh
@@ -114,7 +114,7 @@ for arch in $ARCHS; do
         -DCMAKE_CXX_FLAGS_INIT="$CFGUARD_CFLAGS" \
         ..
 
-    $BUILDCMD ${CORES+-j$CORES}
+    $BUILDCMD ${CORES:+-j${CORES}}
     $BUILDCMD install
     cd ..
 done
diff --git a/build-lldb-mi.sh b/build-lldb-mi.sh
index cdd2ddd..165c659 100755
--- a/build-lldb-mi.sh
+++ b/build-lldb-mi.sh
@@ -147,4 +147,4 @@ cmake \
     $CMAKEFLAGS \
     ..
 
-$BUILDCMD ${CORES+-j$CORES} install/strip
+$BUILDCMD ${CORES:+-j${CORES}} install/strip
diff --git a/build-llvm.sh b/build-llvm.sh
index 60e90f9..c7b809c 100755
--- a/build-llvm.sh
+++ b/build-llvm.sh
@@ -309,6 +309,6 @@ cmake \
     $CMAKEFLAGS \
     ..
 
-$BUILDCMD ${CORES+-j$CORES} install/strip
+$BUILDCMD ${CORES:+-j${CORES}} install/strip
 
 cp ../LICENSE.TXT $PREFIX
diff --git a/build-openmp.sh b/build-openmp.sh
index 90a33e8..de57c88 100755
--- a/build-openmp.sh
+++ b/build-openmp.sh
@@ -95,7 +95,7 @@ for arch in $ARCHS; do
         -DCMAKE_CXX_FLAGS_INIT="$CFGUARD_CFLAGS" \
         $CMAKEFLAGS \
         ..
-    $BUILDCMD ${CORES+-j$CORES}
+    $BUILDCMD ${CORES:+-j${CORES}}
     $BUILDCMD install
     rm -f $PREFIX/$arch-w64-mingw32/bin/*iomp5md*
     rm -f $PREFIX/$arch-w64-mingw32/lib/*iomp5md*