diff --git a/.github/workflows/CI-unixish.yml b/.github/workflows/CI-unixish.yml
index 9b720b95b4a..ee7d9cad034 100644
--- a/.github/workflows/CI-unixish.yml
+++ b/.github/workflows/CI-unixish.yml
@@ -241,7 +241,7 @@ jobs:
 
       - name: Check syntax with NONNEG
         run: |
-          ls lib/*.cpp | xargs -n 1 -P $(nproc) g++ -fsyntax-only -std=c++0x -Ilib -Iexternals -Iexternals/picojson -Iexternals/simplecpp -Iexternals/tinyxml2 -DNONNEG
+          make check-nonneg
 
   build_cmake_boost:
 
diff --git a/Makefile b/Makefile
index 3a8403a1e38..0c3c979e95c 100644
--- a/Makefile
+++ b/Makefile
@@ -453,6 +453,9 @@ checkCWEEntries: /tmp/errorlist.xml
 .PHONY: validateRules
 validateRules:
 	xmllint --noout rules/*.xml
+.PHONY: check-nonneg
+check-nonneg:
+	ls lib/*.cpp | xargs -n 1 -P $$(nproc) g++ -fsyntax-only -DNONNEG $(CXXFLAGS) $(INCLUDE_FOR_LIB)
 
 ###### Build
 
diff --git a/lib/astutils.cpp b/lib/astutils.cpp
index 8e6ee974f15..ad2a2e05ea7 100644
--- a/lib/astutils.cpp
+++ b/lib/astutils.cpp
@@ -109,7 +109,7 @@ static int getArgumentPos(const Token* ftok, const Token* tokToFind){
 }
 
 template<class T, class OuputIterator, REQUIRES("T must be a Token class", std::is_convertible<T*, const Token*> )>
-static void astFlattenCopy(T* tok, const char* op, OuputIterator out, nonneg int depth = 100)
+static void astFlattenCopy(T* tok, const char* op, OuputIterator out, int depth = 100)
 {
     --depth;
     if (!tok || depth < 0)
diff --git a/tools/dmake/dmake.cpp b/tools/dmake/dmake.cpp
index e5748ebf389..a9c5248706b 100644
--- a/tools/dmake/dmake.cpp
+++ b/tools/dmake/dmake.cpp
@@ -867,6 +867,10 @@ int main(int argc, char **argv)
     fout << ".PHONY: validateRules\n";
     fout << "validateRules:\n";
     fout << "\txmllint --noout rules/*.xml\n";
+    fout << ".PHONY: check-nonneg\n";
+    fout << "check-nonneg:\n";
+    // TODO: how to use provided number of jobs?
+    fout << "\tls lib/*.cpp | xargs -n 1 -P $$(nproc) g++ -fsyntax-only -DNONNEG $(CXXFLAGS) $(INCLUDE_FOR_LIB)\n";
 
     fout << "\n###### Build\n\n";