diff --git a/src/sp65/input.c b/src/sp65/input.c
index 735e4920c..a34e527e7 100644
--- a/src/sp65/input.c
+++ b/src/sp65/input.c
@@ -33,6 +33,8 @@
 
 
 
+#include <stdlib.h>
+
 /* common */
 #include "fileid.h"
 
@@ -78,14 +80,27 @@ static const FileId FormatTable[] = {
 
 
 
+static int Compare (const void* Key, const void* Id)
+/* Compare function for bsearch */
+{
+    return strcmp (Key, ((const FileId*) Id)->Ext);
+}
+
+
+
 int FindInputFormat (const char* Name)
 /* Find an input format by name. The function returns a value less than zero
  * if Name is not a known input format.
  */
 {
-    /* Search for the entry in the table */
-    const FileId* F = GetFileId (Name, FormatTable,
-                                 sizeof (FormatTable) / sizeof (FormatTable[0]));
+    /* Search for the entry in the table. */
+    const FileId* F = bsearch (Name,
+                               FormatTable,
+                               sizeof (FormatTable) / sizeof (FormatTable[0]),
+                               sizeof (FormatTable[0]),
+                               Compare);
+
+    /* Return the id or an error code */
     return (F == 0)? -1 : F->Id;
 }
 
diff --git a/src/sp65/main.c b/src/sp65/main.c
index cd159a1b3..a49b69fbe 100644
--- a/src/sp65/main.c
+++ b/src/sp65/main.c
@@ -118,7 +118,7 @@ static void OptRead (const char* Opt, const char* Arg)
     const char* Format = GetAttrVal (C, "format");
     if (Format != 0) {
         IF = FindInputFormat (Format);
-        if (IF <= 0) {
+        if (IF < 0) {
             Error ("Unknown input format `%s'", Format);
         }
     }