diff --git a/src/head-go-version b/src/head-go-version
deleted file mode 100755
index 7767486..0000000
--- a/src/head-go-version
+++ /dev/null
@@ -1,28 +0,0 @@
-#!/bin/bash
-
-set -e
-[ -n "$DEBUG" ] && set -x
-
-CDPATH="" cd -- "$(dirname -- "$(dirname -- "$0")")"
-
-. src/lib
-
-debug_out starting head-go-version
-
-version="$1"
-
-mock_head_go_version="${mock_head_go_version:-""}"
-if [ -n "$mock_head_go_version" ]; then
-  available_head_versions="${available_head_versions:-""}"
-  for ver in $available_head_versions; do
-    if [ "$ver" = "$version" ]; then
-      exit 0
-    fi
-  done
-  exit 1
-fi
-
-. src/lib
-
-check_url="$(download_go_url "$version")"
-curl -IL --fail -s "$check_url" >/dev/null
diff --git a/src/lib b/src/lib
index c404c08..8d45b83 100755
--- a/src/lib
+++ b/src/lib
@@ -113,3 +113,8 @@ exe_name() {
   [ "$(goos)" = "windows" ] && suffix=".exe"
   echo "$1$suffix"
 }
+
+is_precise_version() {
+  [[ $1 =~ ^[0-9]+(.[0-9]+(.[0-9]+)?)?([A-Za-z0-9]+)?$ ]] && return
+  return 1
+}
diff --git a/src/lib_test.sh b/src/lib_test.sh
index 3874211..142b83a 100755
--- a/src/lib_test.sh
+++ b/src/lib_test.sh
@@ -31,4 +31,33 @@ test_download_go_url() {
     "$(RUNNER_OS=Windows download_go_url "1.15.5")"
 }
 
+test_is_precise_version() {
+  versions='
+1
+1.15
+1.15.1
+1.1.1
+9999.9999.9999
+1.15beta1
+  '
+
+  for v in $versions; do
+    is_precise_version "$v"
+    assertTrue "$v" $?
+  done
+
+  not_versions='
+*
+1.x
+1.15.x
+^ 1.15.1
+  '
+
+  echo "$not_versions" | while IFS= read -r v; do
+    is_precise_version "$v"
+    assertFalse "$v" $?
+  done
+
+}
+
 . ./third_party/shunit2/shunit2
diff --git a/src/resolve-go-version b/src/resolve-go-version
index 7898c1b..a5c92dd 100755
--- a/src/resolve-go-version
+++ b/src/resolve-go-version
@@ -19,6 +19,11 @@ debug_out starting resolve-go-version
 GO_VERSION_CONSTRAINT="$1"
 GO_TOOL_CACHE="$2"
 
+if is_precise_version "$GO_VERSION_CONSTRAINT"; then
+  echo "$GO_VERSION_CONSTRAINT"
+  exit
+fi
+
 # special case for gotip
 if [ "$GO_VERSION_CONSTRAINT" = "gotip" ] || [ "$GO_VERSION_CONSTRAINT" = "tip" ]; then
   echo "tip"
@@ -39,21 +44,6 @@ if [ -z "$IGNORE_LOCAL_GO" ]; then
   done
 fi
 
-head_go_version="${head_go_version:-"./src/head-go-version"}"
-
-# if the exact version is available to download, use it
-if  "$head_go_version" "$GO_VERSION_CONSTRAINT" ; then
-  echo "$GO_VERSION_CONSTRAINT"
-  exit
-fi
-
-## if the exact version is available to download, use it
-#check_url="$(download_go_url "$GO_VERSION_CONSTRAINT")"
-#if curl -IL --fail -s "$check_url" >/dev/null; then
-#  echo "$GO_VERSION_CONSTRAINT"
-#  exit
-#fi
-
 if [ -z "$IGNORE_LOCAL_GO" ]; then
   set +e
   local_matches="$(echo "$local_versions" | "$action_dir/third_party/sh-semver/semver.sh" -r "$GO_VERSION_CONSTRAINT")"
diff --git a/src/resolve-go-version_test.sh b/src/resolve-go-version_test.sh
index f35c58a..c1bae75 100755
--- a/src/resolve-go-version_test.sh
+++ b/src/resolve-go-version_test.sh
@@ -38,23 +38,6 @@ oneTimeSetUp() {
   done
 }
 
-available_head_versions=''
-
-mock_version_available_to_dl() {
-  v="$1"
-  for ver in $available_head_versions ; do
-      if [ "$ver" = "$v" ]; then
-        return 0
-      fi
-  done
-  return 1
-}
-
-mock_head_versions() {
-  export available_head_versions="$1"
-  export mock_head_go_version="1"
-}
-
 test_version() {
   export dl_json="$ex_dl_json"
   tmpdir="$SHUNIT_TMPDIR/${FUNCNAME[0]}"
@@ -62,8 +45,6 @@ test_version() {
   mkdir -p "$toolcache"
   touch "$toolcache/1.14.2"
   touch "$toolcache/1.15.6"
-  mock_head_versions '1.15
-1.15beta1'
 
   tests='*;1.15.6
 1.15;1.15
@@ -81,7 +62,6 @@ tip;tip
   done
 }
 
-
 test_version_ignore_local_go() {
   export dl_json="$ex_dl_json"
   tmpdir="$SHUNIT_TMPDIR/${FUNCNAME[0]}"
@@ -89,10 +69,6 @@ test_version_ignore_local_go() {
   mkdir -p "$toolcache"
   touch "$toolcache/1.14.2"
   touch "$toolcache/1.15.6"
-    mock_head_versions '1.15
-1.15beta1'
-
-  export version_available_to_dl_func="mock_version_available_to_dl"
 
   tests='*;1.15.7
 1.15;1.15