diff --git a/cover/profile.go b/cover/profile.go
index 79009d0f70..0bb3541774 100644
--- a/cover/profile.go
+++ b/cover/profile.go
@@ -168,6 +168,9 @@ func seekBack(l string, sep byte, end int, what string) (value int, nextSep int,
 			if err != nil {
 				return 0, 0, fmt.Errorf("couldn't parse %q: %v", what, err)
 			}
+			if i < 0 {
+				return 0, 0, fmt.Errorf("negative values are not allowed for %s, found %d", what, i)
+			}
 			return i, start, nil
 		}
 	}
diff --git a/cover/profile_test.go b/cover/profile_test.go
index f312cf05fe..3cecdacd50 100644
--- a/cover/profile_test.go
+++ b/cover/profile_test.go
@@ -198,6 +198,12 @@ some/fancy/path:42.69,44.16 2`,
 :42.69,44.16 2 3`,
 			expectErr: true,
 		},
+		{
+			name: "a negative count is an error",
+			input: `mode: count
+some/fancy/path:42.69,44.16 2 -1`,
+			expectErr: true,
+		},
 	}
 
 	for _, tc := range tests {