diff --git a/src/modules/Gmp/mpq.cmod b/src/modules/Gmp/mpq.cmod
index fec5d2abac5b625ce69dc3e1239e49a48be5adf1..5b9ba05c7e7962ed07d48f338fbdf6944107ec88 100644
--- a/src/modules/Gmp/mpq.cmod
+++ b/src/modules/Gmp/mpq.cmod
@@ -372,7 +372,7 @@ PIKECLASS mpq
       prec++;
       /* present 'num' and insert dot */
       len += 3;
-      s = begin_shared_string(len);
+      s = begin_shared_string(len + 1);	  /* +1 to cater for a leading 0 */
       if(len/2 > prec)
       {
 	/* Shift the integer part forward to make room for the dot. */
@@ -394,6 +394,11 @@ PIKECLASS mpq
 		prec+1);
 	len++;
       }
+      /* Make sure numbers start with a digit */
+      if ((len == prec) || ((unsigned)(s->str[len-prec-1] - '0') > 9)) {
+        memmove(s->str+len-prec+1, s->str+len-prec, prec);
+        s->str[len++ -prec] = '0';
+      }
       s->str[len-prec]='.';
       push_string (end_and_resize_shared_string (s, len));
     }
diff --git a/src/modules/Gmp/testsuite.in b/src/modules/Gmp/testsuite.in
index 7b568cca4b35fc1b5dfe18076fb760920ec04a29..dbd025eb98aa826d2b5ffac2892e7f66aebdd0a3 100644
--- a/src/modules/Gmp/testsuite.in
+++ b/src/modules/Gmp/testsuite.in
@@ -320,6 +320,12 @@ cond_begin([[ master()->resolv("Gmp")->mpq ]])
   test_true(stringp((string)Gmp.mpq(17)))
   test_eq((string)Gmp.mpq(17),"17")
   test_eq((string)Gmp.mpq(1.25),"1.25")
+  test_eq((string)Gmp.mpq(0.25),"0.25")
+  test_eq((string)Gmp.mpq(-0.25),"-0.25")
+  test_eq((string)Gmp.mpq(0.5), "0.5")
+  test_eq((string)Gmp.mpq(-0.5), "-0.5")
+  test_eq((string)Gmp.mpq(0.75),"0.75")
+  test_eq((string)Gmp.mpq(-0.75),"-0.75")
   test_eq((int)Gmp.mpq(17),17)
   test_false(Gmp.mpq(0))
   test_true(Gmp.mpq(1))