diff --git a/src/asm/globlex.c b/src/asm/globlex.c
index b9d7e96d..12bb1e4e 100644
--- a/src/asm/globlex.c
+++ b/src/asm/globlex.c
@@ -100,7 +100,13 @@ static int32_t ascii2bin(char *s)
 		break;
 	}
 
-	if (radix == 4) {
+	if (*s == '\0') {
+		/*
+		 * There are no digits after the radix prefix
+		 * (or the string is empty, which shouldn't happen).
+		 */
+		yyerror("Invalid integer constant");
+	} else if (radix == 4) {
 		int32_t c;
 
 		while (*s != '\0') {
diff --git a/test/asm/divzero-section-bank.out b/test/asm/divzero-section-bank.out
index b382e48f..553b2800 100644
--- a/test/asm/divzero-section-bank.out
+++ b/test/asm/divzero-section-bank.out
@@ -1,2 +1,4 @@
+ERROR: divzero-section-bank.asm(1):
+    Invalid integer constant
 ERROR: divzero-section-bank.asm(1):
     Division by zero