diff --git a/win/nmakehlp.c b/win/nmakehlp.c
index 8482577..5be8ca7 100644
--- a/win/nmakehlp.c
+++ b/win/nmakehlp.c
@@ -271,7 +271,7 @@ CheckForCompilerFeature(
     if (!ok) {
 	DWORD err = GetLastError();
 	int chars = snprintf(msg, sizeof(msg) - 1,
-		"Tried to launch: \"%s\", but got error [%lu]: ", cmdline, err);
+		"Tried to launch: \"%s\", but got error [%u]: ", cmdline, err);
 
 	FormatMessage(FORMAT_MESSAGE_FROM_SYSTEM|FORMAT_MESSAGE_IGNORE_INSERTS|
 		FORMAT_MESSAGE_MAX_WIDTH_MASK, 0L, err, 0, (LPSTR)&msg[chars],
@@ -405,7 +405,7 @@ CheckForLinkerFeature(
     if (!ok) {
 	DWORD err = GetLastError();
 	int chars = snprintf(msg, sizeof(msg) - 1,
-		"Tried to launch: \"%s\", but got error [%lu]: ", cmdline, err);
+		"Tried to launch: \"%s\", but got error [%u]: ", cmdline, err);
 
 	FormatMessage(FORMAT_MESSAGE_FROM_SYSTEM|FORMAT_MESSAGE_IGNORE_INSERTS|
 		FORMAT_MESSAGE_MAX_WIDTH_MASK, 0L, err, 0, (LPSTR)&msg[chars],