diff --git a/emsdk.py b/emsdk.py
index a1d15d9..e130078 100644
--- a/emsdk.py
+++ b/emsdk.py
@@ -2497,19 +2497,6 @@ def can_simultaneously_activate(tool1, tool2):
   return tool1.id != tool2.id
 
 
-def remove_nonexisting_tools(tool_list, log_errors=True):
-  i = 0
-  while i < len(tool_list):
-    tool = tool_list[i]
-    if not tool.is_installed():
-      if log_errors:
-        errlog("Warning: The SDK/tool '" + str(tool) + "' cannot be activated since it is not installed! Skipping this tool...")
-      tool_list.pop(i)
-      continue
-    i += 1
-  return tool_list
-
-
 # Expands dependencies for each tool, and removes ones that don't exist.
 def process_tool_list(tools_to_activate, log_errors=True):
   i = 0
@@ -2520,7 +2507,9 @@ def process_tool_list(tools_to_activate, log_errors=True):
     tools_to_activate = tools_to_activate[:i] + deps + tools_to_activate[i:]
     i += len(deps) + 1
 
-  tools_to_activate = remove_nonexisting_tools(tools_to_activate, log_errors=log_errors)
+  for tool in tools_to_activate:
+    if not tool.is_installed():
+      exit_with_error("error: tool is not installed and therefore cannot be activated: '%s'" % tool)
 
   # Remove conflicting tools
   i = 0
diff --git a/test/test.py b/test/test.py
index 7b02189..8428149 100755
--- a/test/test.py
+++ b/test/test.py
@@ -64,8 +64,8 @@ def failing_call_with_output(cmd, expected):
   if WINDOWS:
     print('warning: skipping part of failing_call_with_output() due to error codes not being propagated (see #592)')
   else:
-    assert proc.returncode, 'call must have failed: ' + str([stdout, "\n========\n", stderr])
-  assert expected in stdout or expected in stderr, 'call did not have the right output'
+    assert proc.returncode, 'call must have failed: ' + str([stdout, '\n========\n', stderr])
+  assert expected in stdout or expected in stderr, 'call did not have the right output: ' + str([stdout, '\n========\n', stderr])
 
 
 def hack_emsdk(marker, replacement):
@@ -262,6 +262,10 @@ int main() {
     # Test that its possible to install emscripten as tool instead of SDK
     checked_call_with_output(emsdk + ' install releases-upstream-77b065ace39e6ab21446e13f92897f956c80476a', unexpected='Installing SDK')
 
+  def test_activate_missing(self):
+    run_emsdk('install latest')
+    failing_call_with_output(emsdk + ' activate 2.0.1', expected="error: tool is not installed and therefore cannot be activated: 'releases-upstream-13e29bd55185e3c12802bc090b4507901856b2ba-64bit'")
+
 
 if __name__ == '__main__':
   unittest.main(verbosity=2)