diff --git a/src/tool_urlglob.c b/src/tool_urlglob.c
index 5e73f14766ac84ce90e2b65e153ffc13758756fe..2821d008d4bbaa156a9aa7aac003d60c4c8b5542 100644
--- a/src/tool_urlglob.c
+++ b/src/tool_urlglob.c
@@ -64,7 +64,10 @@ static GlobCode glob_set(URLGlob *glob, char *pattern,
   pat->content.Set.ptr_s = 0;
   pat->content.Set.elements = NULL;
 
-  ++glob->size;
+  if(++glob->size > (GLOB_PATTERN_NUM*2)) {
+    snprintf(glob->errormsg, sizeof(glob->errormsg), "too many globs used\n");
+    return GLOB_ERROR;
+  }
 
   while(!done) {
     switch (*pattern) {
@@ -181,7 +184,10 @@ static GlobCode glob_range(URLGlob *glob, char *pattern,
 
   pat = &glob->pattern[glob->size / 2];
   /* patterns 0,1,2,... correspond to size=1,3,5,... */
-  ++glob->size;
+  if(++glob->size > (GLOB_PATTERN_NUM*2)) {
+    snprintf(glob->errormsg, sizeof(glob->errormsg), "too many globs used\n");
+    return GLOB_ERROR;
+  }
 
   if(ISALPHA(*pattern)) {
     /* character range detected */
diff --git a/src/tool_urlglob.h b/src/tool_urlglob.h
index 9c37f1560c59ee90e9e75a9baf3831a5c2c549c4..9c0813750b573ade422f2e6c521564fd9780f49a 100644
--- a/src/tool_urlglob.h
+++ b/src/tool_urlglob.h
@@ -53,9 +53,12 @@ typedef struct {
   } content;
 } URLPattern;
 
+/* the total number of globs supported */
+#define GLOB_PATTERN_NUM 9
+
 typedef struct {
   char *literal[10];
-  URLPattern pattern[9];
+  URLPattern pattern[GLOB_PATTERN_NUM+1];
   size_t size;
   size_t urllen;
   char *glob_buffer;