diff --git a/src/asm/main.cpp b/src/asm/main.cpp
index bc79014a..bd0f0917 100644
--- a/src/asm/main.cpp
+++ b/src/asm/main.cpp
@@ -267,6 +267,7 @@ static void parseArg(int ch, char *arg) {
 	}
 
 	case 'r':
+		errno = 0;
 		if (std::optional<uint64_t> maxDepth = parseWholeNumber(arg); !maxDepth) {
 			fatal("Invalid argument for option '-r'");
 		} else if (errno == ERANGE) {
diff --git a/src/asm/opt.cpp b/src/asm/opt.cpp
index 08978d41..70e5c94f 100644
--- a/src/asm/opt.cpp
+++ b/src/asm/opt.cpp
@@ -105,6 +105,7 @@ void opt_Parse(char const *s) {
 		break;
 
 	case 'r':
+		errno = 0;
 		if (std::optional<uint64_t> maxRecursionDepth = parseWholeNumber(s); !maxRecursionDepth) {
 			error("Invalid argument for option 'r'");
 		} else if (errno == ERANGE) {