diff --git a/ale_linters/haskell/argon.vim b/ale_linters/haskell/argon.vim
index d8d75bb..2a3e425 100644
--- a/ale_linters/haskell/argon.vim
+++ b/ale_linters/haskell/argon.vim
@@ -27,28 +27,33 @@ function! ale_linters#haskell#argon#Handle(buffer, lines) abort
     let l:output = []
 
     for l:error in ale#util#FuzzyJSONDecode(a:lines, [])
-        for l:block in l:error.blocks
-            let l:complexity = l:block.complexity
+		if !has_key(l:error, 'blocks')
+			" this cannot be formatted properly into an ALE error
+			execute 'echom ''[argon] '' l:error.message'
+			return l:output
+		endif
+		for l:block in l:error.blocks
+			let l:complexity = l:block.complexity
 
-            if l:complexity >= ale#Var(a:buffer, 'haskell_argon_error_level')
-                let l:type = 'E'
-                let l:max_c = ale#Var(a:buffer, 'haskell_argon_error_level')
-            elseif l:complexity >= ale#Var(a:buffer, 'haskell_argon_warn_level')
-                let l:type = 'W'
-                let l:max_c = ale#Var(a:buffer, 'haskell_argon_warn_level')
-            else
-                let l:type = 'I'
-                let l:max_c = ale#Var(a:buffer, 'haskell_argon_info_level')
-            endif
+			if l:complexity >= ale#Var(a:buffer, 'haskell_argon_error_level')
+				let l:type = 'E'
+				let l:max_c = ale#Var(a:buffer, 'haskell_argon_error_level')
+			elseif l:complexity >= ale#Var(a:buffer, 'haskell_argon_warn_level')
+				let l:type = 'W'
+				let l:max_c = ale#Var(a:buffer, 'haskell_argon_warn_level')
+			else
+				let l:type = 'I'
+				let l:max_c = ale#Var(a:buffer, 'haskell_argon_info_level')
+			endif
 
-            call add(l:output, {
-            \   'filename': l:error.path,
-            \   'lnum': str2nr(l:block.lineno),
-            \   'col': str2nr(l:block.col),
-            \   'text': l:block.name . ': cyclomatic complexity of '  . l:complexity,
-            \   'type': l:type,
-            \})
-        endfor
+			call add(l:output, {
+			\   'filename': l:error.path,
+			\   'lnum': l:block.lineno,
+			\   'col': l:block.col,
+			\   'text': l:block.name . ': cyclomatic complexity of '  . l:complexity,
+			\   'type': l:type,
+			\})
+		endfor
     endfor
 
     return l:output