diff --git a/byte/byte_copy.c b/byte/byte_copy.c
index 9c8da7b..d85431e 100644
--- a/byte/byte_copy.c
+++ b/byte/byte_copy.c
@@ -3,12 +3,19 @@
 /* byte_copy copies in[0] to out[0], in[1] to out[1], ... and in[len-1]
  * to out[len-1]. */
 void byte_copy(void* out, size_t len, const void* in) {
-  register char* s=out;
-  register const char* t=in;
-  register const char* u=t+len;
+  char* s=out;
+  const char* t=in;
+#if 1
+  /* gcc 4.3.1 generates wrong code for this, so I'm switching to
+   * simpler code */
+  size_t i;
+  for (i=0; i<len; ++i)
+    s[i]=t[i];
+#else
+  const char* u=t+len;
   if (len>127) {
     while ((unsigned long)s&(sizeof(unsigned long)-1)) {
-      if (t==u) break; *s=*t; ++s; ++t;
+      *s=*t; ++s; ++t;
     }
     /* s (destination) is now unsigned long aligned */
 #ifndef __i386__
@@ -25,4 +32,5 @@ void byte_copy(void* out, size_t len, const void* in) {
     if (t==u) break; *s=*t; ++s; ++t;
     if (t==u) break; *s=*t; ++s; ++t;
   }
+#endif
 }
diff --git a/test/byte_copy.c b/test/byte_copy.c
index aa0cf08..70ad5de 100644
--- a/test/byte_copy.c
+++ b/test/byte_copy.c
@@ -1,15 +1,36 @@
 #include "byte.h"
 #include "errmsg.h"
+#include <string.h>
+
+char buf[4096];
+char text[128];
 
 int main() {
-  char buf[4096];
-  carp("both aligned");
-  byte_copy(buf,16,"this is a test!\n");
-  carp("destination aligned, source unaligned");
-  byte_copy(buf,1000,buf+1);
-  carp("destination unaligned, source aligned");
-  byte_copy(buf+1,1000,buf);
-  carp("both unaligned");
-  byte_copy(buf+1,1000,buf+3);
+  memset(buf,0,sizeof(buf));
+  strcpy(text,"this is a test!\n");
+
+//  carp("both aligned");
+  byte_copy(buf,16,text);
+  if (memcmp(buf,"this is a test!\n\0",18))
+    die(1,"fail 1");
+
+  memset(buf,0,sizeof(buf));
+//  carp("destination aligned, source unaligned");
+  byte_copy(buf,15,text+1);
+  if (memcmp(buf,"his is a test!\n\0\0",18))
+    die(1,"fail 2");
+
+  memset(buf,0,sizeof(buf));
+//  carp("destination unaligned, source aligned");
+  byte_copy(buf+1,15,text);
+  if (memcmp(buf,"\0this is a test!\0\0",18))
+    die(1,"fail 3");
+
+  memset(buf,0,sizeof(buf));
+//  carp("both unaligned");
+  byte_copy(buf+1,10,text+3);
+  if (memcmp(buf,"\0s is a tes\0\0",14))
+    die(1,"fail 4");
+
   return 0;
 }