diff --git a/include/asm/warning.hpp b/include/asm/warning.hpp
index 6862aeed..b479c983 100644
--- a/include/asm/warning.hpp
+++ b/include/asm/warning.hpp
@@ -7,8 +7,6 @@
 
 #include "diagnostics.hpp"
 
-extern unsigned int nbErrors;
-
 enum WarningLevel {
 	LEVEL_DEFAULT,    // Warnings that are enabled by default
 	LEVEL_ALL,        // Warnings that probably indicate an error
@@ -82,4 +80,7 @@ void error(char const *fmt, ...);
 // once.
 void error(std::function<void()> callback);
 
+void forceError();
+void requireZeroErrors();
+
 #endif // RGBDS_ASM_WARNING_HPP
diff --git a/src/asm/main.cpp b/src/asm/main.cpp
index 1ca9ce96..35188150 100644
--- a/src/asm/main.cpp
+++ b/src/asm/main.cpp
@@ -418,8 +418,8 @@ int main(int argc, char *argv[]) {
 	fstk_Init(mainFileName, maxDepth);
 
 	// Perform parse (`yy::parser` is auto-generated from `parser.y`)
-	if (yy::parser parser; parser.parse() != 0 && nbErrors == 0) {
-		nbErrors = 1;
+	if (yy::parser parser; parser.parse() != 0) {
+		forceError();
 	}
 
 	if (!fstk_FailedOnMissingInclude()) {
@@ -432,10 +432,7 @@ int main(int argc, char *argv[]) {
 		sect_CheckStack();
 	}
 
-	if (nbErrors != 0) {
-		fprintf(stderr, "Assembly aborted with %u error%s!\n", nbErrors, nbErrors == 1 ? "" : "s");
-		exit(1);
-	}
+	requireZeroErrors();
 
 	// If parse aborted due to missing an include, and `-MG` was given, exit normally
 	if (fstk_FailedOnMissingInclude()) {
diff --git a/src/asm/warning.cpp b/src/asm/warning.cpp
index afdb3e48..77b460fc 100644
--- a/src/asm/warning.cpp
+++ b/src/asm/warning.cpp
@@ -125,6 +125,19 @@ void fatal(char const *fmt, ...) {
 	exit(1);
 }
 
+void forceError() {
+	if (nbErrors == 0) {
+		nbErrors = 1;
+	}
+}
+
+void requireZeroErrors() {
+	if (nbErrors != 0) {
+		fprintf(stderr, "Assembly aborted with %u error%s!\n", nbErrors, nbErrors == 1 ? "" : "s");
+		exit(1);
+	}
+}
+
 void warning(WarningID id, char const *fmt, ...) {
 	char const *flag = warnings.warningFlags[id].name;
 	va_list args;