diff --git a/textcode/scan_base64.c b/textcode/scan_base64.c
index 648d19e..63f9698 100644
--- a/textcode/scan_base64.c
+++ b/textcode/scan_base64.c
@@ -23,7 +23,7 @@ size_t scan_base64(const char *src,char *dest,size_t *destlen) {
       int equal=(*s=='=');
       while (*s=='=' && ((s-(const unsigned char*)src)&3)) ++s;
       tmp &= ((1<<bits)-1);
-      if (!tmp || equal) { j=i; orig=s; }
+      if (!tmp || equal) { j=i; orig=(const char*)s; }
       break;
     }
     tmp=(tmp<<6)|a; bits+=6;
@@ -32,7 +32,7 @@ size_t scan_base64(const char *src,char *dest,size_t *destlen) {
       bits-=8;
       if (dest) dest[i]=(tmp>>bits);
       ++i;
-      if (!bits) { j=i; orig=s; }
+      if (!bits) { j=i; orig=(const char*)s; }
     }
   }
   if (destlen) *destlen=j;
diff --git a/textcode/scan_jsonescape.c b/textcode/scan_jsonescape.c
index 5383c7c..1e611dc 100644
--- a/textcode/scan_jsonescape.c
+++ b/textcode/scan_jsonescape.c
@@ -57,7 +57,7 @@ size_t scan_jsonescape(const char *src,char *dest,size_t *destlen) {
     }
     if (prev!=(unsigned int)-1) goto abort;
     /* We expect utf-8 incoming. Make sure it's valid. */
-    if (!scan_utf8(s+i,4,NULL)) goto abort;
+    if (!scan_utf8(src+i,4,NULL)) goto abort;
     if (dest) dest[written]=c;
     ++written;
   }
@@ -69,3 +69,36 @@ abort:
   *destlen=written;
   return i;
 }
+
+#ifdef UNITTEST
+#include <assert.h>
+
+int main() {
+  char buf[100];
+  size_t l;
+  assert(scan_jsonescape("fnord",buf,&l)==5 && l==5 && !memcmp(buf,"fnord",5));
+  /* is \n properly unescaped? */
+  assert(scan_jsonescape("a\\nb",buf,&l)==4 && l==3 && !memcmp(buf,"a\nb",3));
+  assert(scan_jsonescape("a\\rb",buf,&l)==4 && l==3 && !memcmp(buf,"a\rb",3));
+  assert(scan_jsonescape("a\\bb",buf,&l)==4 && l==3 && !memcmp(buf,"a\bb",3));
+  assert(scan_jsonescape("a\\fb",buf,&l)==4 && l==3 && !memcmp(buf,"a\fb",3));
+  assert(scan_jsonescape("a\\tb",buf,&l)==4 && l==3 && !memcmp(buf,"a\tb",3));
+  assert(scan_jsonescape("a\\\\b",buf,&l)==4 && l==3 && !memcmp(buf,"a\\b",3));
+  assert(scan_jsonescape("a\\/b",buf,&l)==4 && l==3 && !memcmp(buf,"a/b",3));
+  assert(scan_jsonescape("a\\\"b",buf,&l)==4 && l==3 && !memcmp(buf,"a\"b",3));
+  /* does a double quote end the string? */
+  assert(scan_jsonescape("a\"b",buf,&l)==1 && l==1 && !memcmp(buf,"a",1));
+  /* how about unicode escape */
+  assert(scan_jsonescape("a\\u005cb",buf,&l)==8 && l==3 && !memcmp(buf,"a\\b",3));
+  /* a trailing surrogate pair with no lead before it */
+  assert(scan_jsonescape("a\\udead\"",buf,&l)==1);
+  /* a lead surrogate pair with no trailer behind it */
+  assert(scan_jsonescape("a\\udafd\"",buf,&l)==1);
+  assert(scan_jsonescape("a\\udafd\\udafd",buf,&l)==1);
+  assert(scan_jsonescape("a\\udafd0",buf,&l)==1);
+  /* correct surrogate pair */
+  assert(scan_jsonescape("a\\ud834\\udd1eb",buf,&l)==14 && l==6 && !memcmp(buf,"a\xf0\x9d\x84\x9e""b",6));
+  /* how about some incorrect UTF-8? */
+  assert(scan_jsonescape("a\xc0\xaf",buf,&l)==1 && l==1 && !memcmp(buf,"a",1));
+}
+#endif