diff --git a/NEWS.md b/NEWS.md
index 69ac90ecc2b09..af1aee2f30135 100644
--- a/NEWS.md
+++ b/NEWS.md
@@ -10,6 +10,8 @@ New language features
 Language changes
 ----------------
 
+  * The syntax `1.+2` is deprecated, since it is ambiguous: it could mean either
+    `1 .+ 2` (the current meaning) or `1. + 2` ([#19089]).
 
 Breaking changes
 ----------------
diff --git a/base/sparse/linalg.jl b/base/sparse/linalg.jl
index 2e63f6b63dc83..c56f8a931229b 100644
--- a/base/sparse/linalg.jl
+++ b/base/sparse/linalg.jl
@@ -611,7 +611,7 @@ function normestinv(A::SparseMatrixCSC{T}, t::Integer = min(2,maximum(size(A))))
             end
         end
     end
-    scale!(X, 1./n)
+    scale!(X, 1 ./ n)
 
     iter = 0
     local est
diff --git a/doc/src/manual/mathematical-operations.md b/doc/src/manual/mathematical-operations.md
index a6ff8bdea53f8..d23a27cdce942 100644
--- a/doc/src/manual/mathematical-operations.md
+++ b/doc/src/manual/mathematical-operations.md
@@ -169,6 +169,11 @@ For example, if you define `⊗(A,B) = kron(A,B)` to give a convenient
 infix syntax `A ⊗ B` for Kronecker products ([`kron`](@ref)), then
 `[A,B] .⊗ [C,D]` will compute `[A⊗C, B⊗D]` with no additional coding.
 
+Combining dot operators with numeric literals can be ambiguous.
+For example, it is not clear whether `1.+x` means `1. + x` or `1 .+ x`.
+Therefore this syntax is disallowed, and spaces must be used around
+the operator in such cases.
+
 ## Numeric Comparisons
 
 Standard comparison operations are defined for all the primitive numeric types:
diff --git a/src/julia-parser.scm b/src/julia-parser.scm
index e15e23d7fb016..e8c5998ed69e0 100644
--- a/src/julia-parser.scm
+++ b/src/julia-parser.scm
@@ -306,7 +306,13 @@
     (if (eqv? (peek-char port) #\.)
         (begin (read-char port)
                (if (dot-opchar? (peek-char port))
-                   (io.ungetc port #\.)
+                   (begin
+                     (if (not (eqv? (peek-char port) #\.))
+                         (let ((num (get-output-string str)))
+                           (syntax-deprecation port
+                                               (string num #\. (peek-char port))
+                                               (string num " ." (peek-char port)))))
+                     (io.ungetc port #\.))
                    (begin (write-char #\. str)
                           (read-digs #f #t)
                           (if (eq? pred char-hex?)
diff --git a/test/arrayops.jl b/test/arrayops.jl
index 56a06f325628a..d4a3e1ba01735 100644
--- a/test/arrayops.jl
+++ b/test/arrayops.jl
@@ -16,31 +16,31 @@ using TestHelpers.OAs
     @test length((1,)) == 1
     @test length((1,2)) == 2
 
-    @test isequal(1.+[1,2,3], [2,3,4])
-    @test isequal([1,2,3].+1, [2,3,4])
-    @test isequal(1.-[1,2,3], [0,-1,-2])
-    @test isequal([1,2,3].-1, [0,1,2])
+    @test isequal(1 .+ [1,2,3], [2,3,4])
+    @test isequal([1,2,3] .+ 1, [2,3,4])
+    @test isequal(1 .- [1,2,3], [0,-1,-2])
+    @test isequal([1,2,3] .- 1, [0,1,2])
 
     @test isequal(5*[1,2,3], [5,10,15])
     @test isequal([1,2,3]*5, [5,10,15])
-    @test isequal(1./[1,2,5], [1.0,0.5,0.2])
+    @test isequal(1 ./ [1,2,5], [1.0,0.5,0.2])
     @test isequal([1,2,3]/5, [0.2,0.4,0.6])
 
-    @test isequal(2.%[1,2,3], [0,0,2])
-    @test isequal([1,2,3].%2, [1,0,1])
-    @test isequal(2.÷[1,2,3], [2,1,0])
-    @test isequal([1,2,3].÷2, [0,1,1])
-    @test isequal(-2.%[1,2,3], [0,0,-2])
+    @test isequal(2 .% [1,2,3], [0,0,2])
+    @test isequal([1,2,3] .% 2, [1,0,1])
+    @test isequal(2 .÷ [1,2,3], [2,1,0])
+    @test isequal([1,2,3] .÷ 2, [0,1,1])
+    @test isequal(-2 .% [1,2,3], [0,0,-2])
     @test isequal([-1,-2,-3].%2, [-1,0,-1])
-    @test isequal(-2.÷[1,2,3], [-2,-1,0])
-    @test isequal([-1,-2,-3].÷2, [0,-1,-1])
+    @test isequal(-2 .÷ [1,2,3], [-2,-1,0])
+    @test isequal([-1,-2,-3] .÷ 2, [0,-1,-1])
 
-    @test isequal(1.<<[1,2,5], [2,4,32])
-    @test isequal(128.>>[1,2,5], [64,32,4])
-    @test isequal(2.>>1, 1)
-    @test isequal(1.<<1, 2)
-    @test isequal([1,2,5].<<[1,2,5], [2,8,160])
-    @test isequal([10,20,50].>>[1,2,5], [5,5,1])
+    @test isequal(1 .<< [1,2,5], [2,4,32])
+    @test isequal(128 .>> [1,2,5], [64,32,4])
+    @test isequal(2 .>> 1, 1)
+    @test isequal(1 .<< 1, 2)
+    @test isequal([1,2,5] .<< [1,2,5], [2,8,160])
+    @test isequal([10,20,50] .>> [1,2,5], [5,5,1])
 
 
     a = ones(2,2)
@@ -1182,8 +1182,8 @@ end
             @test [1,2] ⊙ [3,4] == 11
         end
 
-        @test_throws DomainError (10.^[-1])[1] == 0.1
-        @test (10.^[-1.])[1] == 0.1
+        @test_throws DomainError (10 .^ [-1])[1] == 0.1
+        @test (10 .^ [-1.])[1] == 0.1
     end
 end
 
diff --git a/test/linalg/dense.jl b/test/linalg/dense.jl
index 74d26f0601c93..501acb6f9d2b2 100644
--- a/test/linalg/dense.jl
+++ b/test/linalg/dense.jl
@@ -278,7 +278,7 @@ end
 
                     # Against vectorized versions
                     @test norm(x,-Inf) ≈ minimum(abs.(x))
-                    @test norm(x,-1) ≈ inv(sum(1./abs.(x)))
+                    @test norm(x,-1) ≈ inv(sum(1 ./ abs.(x)))
                     @test norm(x,0) ≈ sum(x .!= 0)
                     @test norm(x,1) ≈ sum(abs.(x))
                     @test norm(x) ≈ sqrt(sum(abs2.(x)))
@@ -362,7 +362,7 @@ end
 
 ## Issue related tests
 @testset "issue #1447" begin
-    A = [1.+0.0im 0; 0 1]
+    A = [1.0+0.0im 0; 0 1]
     B = pinv(A)
     for i = 1:4
         @test A[i] ≈ B[i]
diff --git a/test/parse.jl b/test/parse.jl
index d07c558179be9..07b9c93bdab95 100644
--- a/test/parse.jl
+++ b/test/parse.jl
@@ -21,9 +21,9 @@ end
 # issue #9684
 let
     undot(op) = Symbol(string(op)[2:end])
-    for (ex1, ex2) in [("5.≠x", "5.!=x"),
-                       ("5.≥x", "5.>=x"),
-                       ("5.≤x", "5.<=x")]
+    for (ex1, ex2) in [("5 .≠ x", "5 .!= x"),
+                       ("5 .≥ x", "5 .>= x"),
+                       ("5 .≤ x", "5 .<= x")]
         ex1 = parse(ex1); ex2 = parse(ex2)
         @test ex1.head === :call && (ex1.head === ex2.head)
         @test ex1.args[2] === 5 && ex2.args[2] === 5
diff --git a/test/perf/kernel/laplace.jl b/test/perf/kernel/laplace.jl
index 010adc2bd43e0..9c8365872a18c 100644
--- a/test/perf/kernel/laplace.jl
+++ b/test/perf/kernel/laplace.jl
@@ -5,7 +5,7 @@ function laplace_iter_devec(u, dx2, dy2, Niter, N)
     for iter = 1:Niter
         for i = 2:N-1
             for j = 2:N-1
-                uout[i,j] = ( (u[i-1,j]+u[i+1,j])*dy2 + (u[i,j-1]+u[i,j+1])*dx2 ) * (1./(2*(dx2+dy2)))
+                uout[i,j] = ( (u[i-1,j]+u[i+1,j])*dy2 + (u[i,j-1]+u[i,j+1])*dx2 ) * (1 ./ (2*(dx2+dy2)))
             end
         end
         u, uout = uout, u
@@ -24,7 +24,7 @@ end
 
 function laplace_iter_vec(u, dx2, dy2, Niter, N)
     for i = 1:Niter
-        u[2:N-1, 2:N-1] = ((u[1:N-2, 2:N-1] + u[3:N, 2:N-1])*dy2 + (u[2:N-1,1:N-2] + u[2:N-1, 3:N])*dx2) * (1./ (2*(dx2+dy2)))
+        u[2:N-1, 2:N-1] = ((u[1:N-2, 2:N-1] + u[3:N, 2:N-1])*dy2 + (u[2:N-1,1:N-2] + u[2:N-1, 3:N])*dx2) * (1 ./ (2*(dx2+dy2)))
     end
     return u
 end
@@ -40,7 +40,7 @@ end
 
 function laplace_iter_vec_sub(u, dx2, dy2, Niter, N)
     for i = 1:Niter
-        u[2:N-1, 2:N-1] = ((view(u, 1:N-2, 2:N-1) + view(u,3:N, 2:N-1))*dy2 + (view(u,2:N-1,1:N-2) + view(u,2:N-1, 3:N))*dx2) * (1./ (2*(dx2+dy2)))
+        u[2:N-1, 2:N-1] = ((view(u, 1:N-2, 2:N-1) + view(u,3:N, 2:N-1))*dy2 + (view(u,2:N-1,1:N-2) + view(u,2:N-1, 3:N))*dx2) * (1 ./ (2*(dx2+dy2)))
     end
     return u
 end
diff --git a/test/perf/kernel/raytracer.jl b/test/perf/kernel/raytracer.jl
index 78c1a131f95a5..b3451222f4402 100644
--- a/test/perf/kernel/raytracer.jl
+++ b/test/perf/kernel/raytracer.jl
@@ -129,7 +129,7 @@ function Raytracer(levels, n, ss)
             g = 0.
             for dx in 0:1:(ss-1)
                 for dy in 0:1:(ss-1)
-                    d = Vec(x+dx*1./ss-n/2., y+dy*1./ss-n/2., n*1.0)
+                    d = Vec(x+dx*1.0/ss-n/2.0, y+dy*1.0/ss-n/2.0, n*1.0)
                     ray = Ray(Vec(0., 0., -4.0), unitize(d))
                     g += ray_trace(light, ray, scene)
                 end
diff --git a/test/perf/micro/perf.jl b/test/perf/micro/perf.jl
index 5f10f1023b3cf..e5686d98d079d 100644
--- a/test/perf/micro/perf.jl
+++ b/test/perf/micro/perf.jl
@@ -101,7 +101,7 @@ function pisumvec()
     s = 0.0
     a = [1:10000]
     for j = 1:500
-        s = sum(1./(a.^2))
+        s = sum(1 ./ (a.^2))
     end
     s
 end
diff --git a/test/perf/spell/perf.jl b/test/perf/spell/perf.jl
index c5a8dee8dc028..4e1bc813f4a22 100644
--- a/test/perf/spell/perf.jl
+++ b/test/perf/spell/perf.jl
@@ -92,7 +92,7 @@ function spelltest(tests; bias=0, verbose=false)
         end
     end
 
-    return Dict("bad"=>bad, "n"=>n, "bias"=>bias, "pct"=>round(Int, 100. - 100.*bad/n),
+    return Dict("bad"=>bad, "n"=>n, "bias"=>bias, "pct"=>round(Int, 100. - 100. * bad/n),
                 "unknown"=>unknown, "secs"=>toc())
 end
 
diff --git a/test/ranges.jl b/test/ranges.jl
index 30b87be782b72..4db7c8cab32ac 100644
--- a/test/ranges.jl
+++ b/test/ranges.jl
@@ -922,8 +922,8 @@ end
 @testset "logspace" begin
     n = 10; a = 2; b = 4
     # test default values; n = 50, base = 10
-    @test logspace(a, b) == logspace(a, b, 50) == 10.^linspace(a, b, 50)
-    @test logspace(a, b, n) == 10.^linspace(a, b, n)
+    @test logspace(a, b) == logspace(a, b, 50) == 10 .^ linspace(a, b, 50)
+    @test logspace(a, b, n) == 10 .^ linspace(a, b, n)
     for base in (10, 2, e)
         @test logspace(a, b, base=base) == logspace(a, b, 50, base=base) == base.^linspace(a, b, 50)
         @test logspace(a, b, n, base=base) == base.^linspace(a, b, n)