diff --git a/src/Parser.jl b/src/Parser.jl
index 6bc5df2..1cd78c1 100644
--- a/src/Parser.jl
+++ b/src/Parser.jl
@@ -393,6 +393,7 @@ function parse_number(pc::ParserContext{<:Any,<:Any,AllowNanInf}, ps::ParserStat
             isint = false
         elseif AllowNanInf && c == LATIN_UPPER_I
             infinity = parse_jsconstant(pc, ps)
+            infinity === nothing && _error("Invalid infinity value", ps)
             resize!(number, 0)
             return (negative ? -infinity : infinity)
         else
diff --git a/src/specialized.jl b/src/specialized.jl
index e0f0e3b..b721994 100644
--- a/src/specialized.jl
+++ b/src/specialized.jl
@@ -145,6 +145,7 @@ function parse_number(pc::ParserContext{<:Any,<:Any,AllowNanInf}, ps::MemoryPars
         elseif AllowNanInf && LATIN_UPPER_I == c
             ps.s = p
             infinity = parse_jsconstant(pc, ps)
+            infinity === nothing && _error("Invalid infinity value", ps)
             return (negative ? -infinity : infinity)
         else
             break