diff --git a/base/parse.jl b/base/parse.jl
index b21d85f7faf99..a652e1f7387ab 100644
--- a/base/parse.jl
+++ b/base/parse.jl
@@ -319,7 +319,7 @@ function tryparse_internal(::Type{Complex{T}}, s::Union{String,SubString{String}
     end
 
     if i₊ == 0 # purely real or imaginary value
-        if iᵢ > 0 # purely imaginary
+        if iᵢ > i && !(iᵢ == i+1 && s[i] in ('+','-')) # purely imaginary (not "±inf")
             x = tryparse_internal(T, s, i, iᵢ-1, raise)
             x === nothing && return nothing
             return Complex{T}(zero(x),x)
diff --git a/src/support/strtod.c b/src/support/strtod.c
index 047d404d90cda..225f2dbd4c933 100644
--- a/src/support/strtod.c
+++ b/src/support/strtod.c
@@ -118,9 +118,16 @@ JL_DLLEXPORT double jl_strtod_c(const char *nptr, char **endptr)
 
     decimal_point_pos = NULL;
 
+    p = nptr;
+
+    /* parse leading spaces */
+    while (isspace((unsigned char)*p)) {
+        p++;
+    }
+
     /* Parse infinities and nans */
-    val = parse_inf_or_nan(nptr, endptr);
-    if (*endptr != nptr)
+    val = parse_inf_or_nan(p, endptr);
+    if (*endptr != p)
         return val;
 
     /* Set errno to zero, so that we can distinguish zero results
@@ -130,12 +137,6 @@ JL_DLLEXPORT double jl_strtod_c(const char *nptr, char **endptr)
     /* We process the optional sign manually, then pass the remainder to
        the system strtod.  This ensures that the result of an underflow
        has the correct sign.  */
-    p = nptr;
-
-    /* parse leading spaces */
-    while (isspace((unsigned char)*p)) {
-        p++;
-    }
 
     /* Process leading sign, if present */
     if (*p == '-') {
diff --git a/test/parse.jl b/test/parse.jl
index 45e13a95b7f90..1d3e064823cf4 100644
--- a/test/parse.jl
+++ b/test/parse.jl
@@ -278,8 +278,8 @@ end
 
 # parsing complex numbers (#22250)
 @testset "complex parsing" begin
-    for r in (1,0,-1), i in (1,0,-1), sign in ('-','+'), Im in ("i","j","im")
-        for s1 in (""," "), s2 in (""," "), s3 in (""," "), s4 in (""," ")
+    for sign in ('-','+'), Im in ("i","j","im"), s1 in (""," "), s2 in (""," "), s3 in (""," "), s4 in (""," ")
+        for r in (1,0,-1), i in (1,0,-1),
             n = Complex(r, sign == '+' ? i : -i)
             s = string(s1, r, s2, sign, s3, i, Im, s4)
             @test n === parse(Complex{Int}, s)
@@ -293,6 +293,13 @@ end
                 @test n*parse(T,"1e-3") == parse(Complex{T}, string(s1, r, "e-3", s2, sign, s3, i, "e-3", Im, s4))
             end
         end
+        for r in (-1.0,-1e-9,Inf,-Inf,NaN), i in (-1.0,-1e-9,Inf,NaN)
+            n = Complex(r, sign == '+' ? i : -i)
+            s = lowercase(string(s1, r, s2, sign, s3, i, Im, s4))
+            @test n === parse(ComplexF64, s)
+            @test Complex(r) === parse(ComplexF64, string(s1, r, s2))
+            @test Complex(0,i) === parse(ComplexF64, string(s3, i, Im, s4))
+        end
     end
     @test parse(Complex{Float16}, "3.3+4i") === Complex{Float16}(3.3+4im)
     @test parse(Complex{Int}, SubString("xxxxxx1+2imxxxx", 7, 10)) === 1+2im
@@ -338,3 +345,10 @@ end
     # Ensure dotting binary doesn't break dotting unary
     @test Meta.parse(".~[1,2]") == Expr(:call, :.~, Expr(:vect, 1, 2))
 end
+
+@testset "inf and nan parsing" begin
+    for (v,vs) in ((NaN,"nan"), (Inf,"inf"), (Inf,"infinity")), sbefore in ("", "  "), safter in ("", "  "), sign in (+, -), case in (lowercase, uppercase)
+        s = case(string(sbefore, sign, vs, safter))
+        @test isequal(parse(Float64, s), sign(v))
+    end
+end