diff --git a/proc/sig.c b/proc/sig.c
index 2191cda5..a93aabb9 100644
--- a/proc/sig.c
+++ b/proc/sig.c
@@ -261,7 +261,7 @@ char *strtosig(const char *restrict s){
       }
     }
   }
-  free(p);
+  free(copy);
   return converted;
 }
 
diff --git a/testsuite/kill.test/kill.exp b/testsuite/kill.test/kill.exp
index 1668ac4f..211395c9 100644
--- a/testsuite/kill.test/kill.exp
+++ b/testsuite/kill.test/kill.exp
@@ -24,6 +24,10 @@ set test "kill convert signal name to number"
 spawn  $kill -lHUP
 expect_pass "$test" "^1\\s*"
 
+set test "kill convert SIG-prefixed signal name to number"
+spawn  $kill -lSIGHUP
+expect_pass "$test" "^1\\s*$"
+
 set test "kill convert signal number to name"
 spawn  $kill -l 1
 expect_pass "$test" "^HUP\\s*"